Removed support for 'dataWrapper' feature.

This feature would cause the library to incorrectly parse responses containing a 'data' field.
Renamed 'data' to 'modelData'

Resources containing a 'data' field were incorrectly created because of the clash in the variable name.
Fixed calculation of headers' size in test
Re-calculate headers' size after stripping proxy string
Lint fixes
Merge pull request #133 from silvolu/master

Spring cleaning