Create a central class for parsing of AJAX parameters in POST/PUT

[christianlupus]

This should make implementing new endpoints simpler and reduces the probability of errors.

[codecov]

Codecov Report

Merging #518 (8fe4c57) into master (542fbc9) will decrease coverage by 0.03%.
The diff coverage is 0.00%.

@@             Coverage Diff             @@
##             master    #518      +/-   ##
===========================================
- Coverage      0.90%   0.87%   -0.04%     
- Complexity      416     436      +20     
===========================================
  Files            13      14       +1     
  Lines          1319    1375      +56     
===========================================
  Hits             12      12              
- Misses         1307    1363      +56     

Flag	Coverage Δ	Complexity Δ
integration	0.00% <0.00%> (ø)	0.00 <23.00> (ø)
unittests	0.87% <0.00%> (-0.04%)	0.00 <23.00> (ø)

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Impacted Files	Coverage Δ	Complexity Δ
lib/Controller/ConfigController.php	0.00% <0.00%> (ø)	7.00 <1.00> (ø)
lib/Controller/MainController.php	0.00% <0.00%> (ø)	33.00 <1.00> (ø)
lib/Controller/RecipeController.php	0.00% <0.00%> (ø)	14.00 <1.00> (ø)
lib/Helper/RestParameterParser.php	0.00% <0.00%> (ø)	20.00 <20.00> (?)