Upgrade alpine in node@8 to 3.6

SimenB · Starefossen · commit 52a90441a676 · 2017-05-31T09:38:05.000+02:00
diff --git a/8.0/alpine/Dockerfile b/8.0/alpine/Dockerfile
@@ -1,4 +1,4 @@
-FROM alpine:3.4
+FROM alpine:3.6
 
 ENV NPM_CONFIG_LOGLEVEL info
 ENV NODE_VERSION 8.0.0
