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
Documentation copy & paste fix
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.
Merge pull request #1902 from jkoepcke/patch-1

Documentation copy & paste fix
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
Remove stray (ignored) semicolon before requestWithMultipartFormRequest: implementation.
Add boundary to copyWithZone for AFHTTPBodyPart
Merge pull request #1919 from robertmryan/master

Add boundary to copyWithZone for AFHTTPBodyPart
Merge pull request #1917 from gfiumara/master

Remove stray semicolon before method implementation
Removes unnecessary call in class constructor
Merge pull request #1929 from fonkadelic/patch-1

Removes unnecessary call in class constructor