chore: convert from callbacks to async

Author: dirkmc

README.md

@@ -38,40 +38,36 @@ This module contains all the necessary code for creating, understanding and vali
 ```js
 const ipns = require('ipns')
 
-ipns.create(privateKey, value, sequenceNumber, lifetime, (err, entryData) => {
-  // your code goes here
-})
+const entryData = await ipns.create(privateKey, value, sequenceNumber, lifetime)
+// your code goes here
 ```
 
 #### Validate record
 
 ```js
 const ipns = require('ipns')
 
-ipns.validate(publicKey, ipnsEntry, (err) => {
-  // your code goes here
-  // if no error, the record is valid
-})
+await ipns.validate(publicKey, ipnsEntry)
+// your code goes here
+// if no error thrown, the record is valid
 ```
 
 #### Embed public key to record
 
 ```js
 const ipns = require('ipns')
 
-ipns.embedPublicKey(publicKey, ipnsEntry, (err, ipnsEntryWithEmbedPublicKey) => {
-  // your code goes here
-})
+const ipnsEntryWithEmbedPublicKey = await ipns.embedPublicKey(publicKey, ipnsEntry)
+// your code goes here
 ```
 
 #### Extract public key from record
 
 ```js
 const ipns = require('ipns')
 
-ipns.extractPublicKey(peerId, ipnsEntry, (err, publicKey) => {
-  // your code goes here
-})
+const publicKey = ipns.extractPublicKey(peerId, ipnsEntry)
+// your code goes here
 ```
 
 #### Datastore key
@@ -93,11 +89,10 @@ Returns a key to be used for storing the ipns entry locally, that is:
 ```js
 const ipns = require('ipns')
 
-ipns.create(privateKey, value, sequenceNumber, lifetime, (err, entryData) => {
-  // ...
-  const marshalledData = ipns.marshal(entryData)
-  // ...
-})
+const entryData = ipns.create(privateKey, value, sequenceNumber, lifetime
+// ...
+const marshalledData = ipns.marshal(entryData)
+// ...
 ```
 
 Returns the entry data serialized.
@@ -120,19 +115,19 @@ const ipns = require('ipns')
 const validator = ipns.validator
 ```
 
-Contains an object with `validate (marshalledData, key, callback)` and `select (dataA, dataB, [callback])` functions.
+Contains an object with `validate (marshalledData, key)` and `select (dataA, dataB)` functions.
 
 The `validate` function aims to verify if an IPNS record is valid. First the record is unmarshalled, then the public key is obtained and finally the record is validated (signature and validity are verified).
 
-The `select` function is responsible for deciding which ipns record is the best (newer) between two records. Both records are unmarshalled and their sequence numbers are compared. If the first record provided is the newer, the operation result will be `0`, otherwise the operation result will be `1`. If a callback is not provided, the response is returned.
+The `select` function is responsible for deciding which ipns record is the best (newer) between two records. Both records are unmarshalled and their sequence numbers are compared. If the first record provided is the newer, the operation result will be `0`, otherwise the operation result will be `1`.
 
 ## API
 
 #### Create record
 
 ```js
 
-ipns.create(privateKey, value, sequenceNumber, lifetime, [callback])
+ipns.create(privateKey, value, sequenceNumber, lifetime)
 ```
 
 Create an IPNS record for being stored in a protocol buffer.
@@ -141,9 +136,8 @@ Create an IPNS record for being stored in a protocol buffer.
 - `value` (string): ipfs path of the object to be published.
 - `sequenceNumber` (Number): number representing the current version of the record.
 - `lifetime` (string): lifetime of the record (in milliseconds).
-- `callback` (function): operation result.
 
-`callback` must follow `function (err, ipnsEntry) {}` signature, where `err` is an error if the operation was not successful. `ipnsEntry` is an object that contains the entry's properties, such as:
+Returns a `Promise` that resolves to an object with the entry's properties eg:
   
 ```js
 {
@@ -159,16 +153,15 @@ Create an IPNS record for being stored in a protocol buffer.
 
 ```js
 
-ipns.validate(publicKey, ipnsEntry, [callback])
+ipns.validate(publicKey, ipnsEntry)
 ```
 
 Validate an IPNS record previously stored in a protocol buffer.
 
 - `publicKey` (`PubKey` [RSA Instance](https://github.com./libp2p/js-libp2p-crypto/blob/master/src/keys/rsa-class.js)): key to be used for cryptographic operations.
 - `ipnsEntry` (Object): ipns entry record (obtained using the create function).
-- `callback` (function): operation result.
 
-`callback` must follow `function (err) {}` signature, where `err` is an error if the operation was not successful. This way, if no error, the validation was successful.
+Throws an error if the validation was not successful.
 
 #### Datastore key
 
@@ -203,16 +196,15 @@ Returns the entry data structure after being serialized.
 #### Embed public key to record
 
 ```js
-ipns.embedPublicKey(publicKey, ipnsEntry, [callback])
+ipns.embedPublicKey(publicKey, ipnsEntry)
 ```
 
 Embed a public key in an IPNS entry. If it is possible to extract the public key from the `peer-id`, there is no need to embed.
 
 - `publicKey` (`PubKey` [RSA Instance](https://github.com./libp2p/js-libp2p-crypto/blob/master/src/keys/rsa-class.js)): key to be used for cryptographic operations.
 - `ipnsEntry` (Object): ipns entry record (obtained using the create function).
-- `callback` (function): operation result.
 
-`callback` must follow `function (err, resultEntry) {}` signature, where `err` is an error if the operation was not successful. This way, if no error, the operation was successful. If the `resultEntry` is also null, the `peer-id` allows to extract the public key from the `peer-id` and there is no need in extracting it.
+ Returns a `Promise`. If the promise resolves to null it means the public key can be extracted directly from the `peer-id`.
 
 #### Extract public key from record
 
@@ -224,9 +216,8 @@ Extract a public key from an IPNS entry.
 
 - `peerId` (`PeerId` [Instance](https://github.com./libp2p/js-peer-id)): peer identifier object.
 - `ipnsEntry` (Object): ipns entry record (obtained using the create function).
-- `callback` (function): operation result.
 
-`callback` must follow `function (err, publicKey) {}` signature, where `err` is an error if the operation was not successful. This way, if no error, the validation was successful. The public key (`PubKey` [RSA Instance](https://github.com./libp2p/js-libp2p-crypto/blob/master/src/keys/rsa-class.js)): may be used for cryptographic operations.
+The returned public key (`PubKey` [RSA Instance](https://github.com./libp2p/js-libp2p-crypto/blob/master/src/keys/rsa-class.js)): may be used for cryptographic operations.
 
 #### Namespace