AFImageCache protocol should inherit from NSObject
fix for import as cocoa touch framework as module to a swift only project

Signed-off-by: Stephan Krusche <krusche@in.tum.de>
Fixes an issue with the request serializer silently handling an error

When a query string serialization block is set on
`AFHTTPRequestSerializer`, if it was to fail with an error it would be
silently handled and the serialization would still return an NSURLRequest.
[Request Serialization] Add `valueForHTTPHeaderField:`

Since we have `setValue:forHTTPHeaderField:` it makes sense to have a
similar method to retrieve them.
Adding test for success block on 204 response
[Issue #2201] Adding @synthesize delegate to AFMultipartBodyStream
Merge branch 'master' of github.com:AFNetworking/AFNetworking
[Issue #2237] Correcting documentation for URLSessionDidFinishEventsForBackgroundURLSession delegate method and reorganizing code accordingly
Merge pull request #2232 from kylef/request-serializer-valueForHTTPHeaderField

[Request Serialization] Add `valueForHTTPHeaderField:`
Minor reformatting
Merge branch 'AFURLRequestSerialization-error' of github.com:kylef/AFNetworking into kylef-AFURLRequestSerialization-error

Conflicts:
	Tests/Tests/AFHTTPRequestSerializationTests.m
Fixing 204 response test
Merge pull request #2206 from krusche/master

fix for import as cocoa touch framework as module to a swift only project
Merge pull request #2179 from marcelofabri/patch-1

AFImageCache protocol should inherit from NSObject
[Issue #2239] Adding [manager.reachabilityManager startMonitoring] to README
Merge branch 'master' of github.com:AFNetworking/AFNetworking
Fixing merge from 61b7a9babab736fc05fc11fb2d2b57e58be982c9
[Issue #2156] Fixing issue caused by passing nil as destination in download task method
Squashed commit of the following:

commit ae493edadcce0b3dd7d0c737ef1611a9c5c313f6
Author: Mattt Thompson <m@mattt.me>
Date:   Tue Aug 12 12:29:47 2014 -0700

    Renaming AFNetworkingOperationFailingURLResponseOriginalDataErrorKey to AFNetworkingOperationFailingURLResponseDataErrorKey

commit 09cf2f758748fe753757af25b9185eb552419708
Merge: efaa26d 66c0736
Author: Mattt Thompson <m@mattt.me>
Date:   Tue Aug 12 12:29:02 2014 -0700

    Merge branch 'getOriginalData' of github.com:yageek/AFNetworking into yageek-getOriginalData

commit 66c07365ad82663e28c76b6cefb15adf6cac2ddb
Author: Yannick Heinrich <yannick.heinrich@gmail.com>
Date:   Thu Jul 24 16:08:29 2014 +0200

    Retrieve data on response deserialisation error

    Add new constant
    `AFNetworkingOperationFailingURLResponseOriginalDataErrorKey` to
    retrieve the original data from the request when the response is
    considered  invalid
[Issue #2244] Conditionally synthesizing delegate for multipart body stream on iOS < 8