Declare the init method on subclasses of AFURLResponseSerialization
[Issue #2339] Added lock/unlock to description method
Replace KVO (which was crashing) with swizzling.
Changing validatesDomainName to readonly property

Clarifying documentation and behavior for validatesDomainName
Copy editing header documentation
Merge https://github.com/AFNetworking/AFNetworking
Fixed construction of the AFSecurityPolicy objects
AFSSLPinningModeNone should not validate the domain name.
Added unit tests to test for the bug.
Relay the downloadFileURL to the delegate if the manager picks a fileURL.
[Issue #2403] Fixing documentation for response serializers
Adding documentation for AFJSONRequestSerializer and AFPropertyListSerializer
Removing charset parameter from Content-Type HTTP header field value
Merge remote-tracking branch 'real/master'

* real/master:
  Removing charset parameter from Content-Type HTTP header field value
  Adding documentation for AFJSONRequestSerializer and AFPropertyListSerializer
  [Issue #2403] Fixing documentation for response serializers
  Copy editing header documentation
  Changing validatesDomainName to readonly property
  Rewriting background session manager warning, duplicating across URL and HTTP session manager
  Document expected session manager usage for background sessions
  Update .cocoadocs.yml
  [Issue #2346] Revert commits related to __has_feature(attribute_availability_app_extension)
  [Issue #2346] Conditionally compile AFNetworkActivityManagerTests
  [Issue #2346] Fix preprocessor directive to pass if __has_feature is unavailable
  [Issue #2346] Adding preprocessor directives around UIApplication network activity indicator
  [Issue #2346] Refactoring preprocessor directives to remove reference to AF_APP_EXTENSION
  Define AF_APP_EXTENSION based on availability with the preprocessor
  Update UIButton+AFNetworking.m
  [Podfile] Update to explicitly define sources
  Adding test for HTTPS request
  Squashed commit of the following:
  Added proper checks for observing AFHTTPRequestSerializerObservedKeyPaths
  Update README.md
Merge https://github.com/AFNetworking/AFNetworking
Merge pull request #2401 from Raizlabs/bugfix/KingOfBrian/PolicyTestErrors

Bugfix: Fix AFSecurityPolicyTests
Merge pull request #2372 from mbjerg/master

[Issue #2369] Added lock/unlock to description method
Merge pull request #2402 from Raizlabs/bugfix/KingOfBrian/FilePathNilWithManagerCompletion

Bugfix: 'filePath' is nil if the manager didFinishDownloadingBlock returns URL
Merge pull request #2352 from arohner/master

Declare the init method on subclasses of AFURLResponseSerialization
Merge pull request #2411 from tangphillip/master

Replace AFURLSessionManager's crashing KVO with method swizzling