[URL Operation] Use the ivar directly in initialization

This is to prevent calling the custom setter inside initialization which
broadcasts KVO notifications and relies on existing state which isn't
yet setup.

Re #1845
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
[URL Operation] Don't allow transitioning to invalid states
Use "long long" instead of "NSInteger" on byte count.

Byte count should always be 64bit integer. Otherwise, AFNetworking won't work on streams
larger than 4GB in 32bits mode. This commit revert the PR #1772 and e94a52c.
Added test to check content type
Explicitly importing MobileCoreServices.
Fixes failing test
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.
Update license year

Fix outdated copyright year (updated to 2014).
The copyright year was out of date. Copyright notices must reflect the current year, so this commit updates the listed year to 2014.

See http://www.copyright.gov/circs/circ01.pdf for more info.
care for 'Content-Length'  on taskDidSendBodyData block
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.