JSON serialization now supports dictionaries and arrays

- The JSON serialization was only allowing dictionaries to be passed in
- The JSON specification allows for both, and the underlying
  serializer NSJSONSerialization also supported both
Fixed a crash caused by autoreleasing NSError object inside the method that was supposed to be passed to the caller by reference using method's argument.
Reworks SSL pinning.
Adds tests for self signed certificates.
Merge pull request #1906 from OliverLetterer/new-ssl-pinning

New SSL pinning.
Merge pull request #1903 from pietrasm/Autoreleased-error-crash-fix

Fixed a crash caused by autoreleasing NSError object inside the method t...
[Issue #1903] Fixing @autorelease patch
Remove unreachable break statements in returning case statement
Merge pull request #1880 from darend/json-serialization-arrays

JSON serialization now supports dictionaries and arrays
Bumping version to 2.2.1

Updating CHANGES