Adds SSLPinningMode to AFURLConnectionOperation and defaultSSLPinMode to AFHTTPClient.
Fixes memory leak.
Gets rid of for loop to check if public key is present.
Compare NSURLRequest rather than NSURL

If you inadvertently load a nil URL in UIImageView+AFNetworking, the failure block of the image request operation is bypassed because [nil isEqual:nil] == NO. By comparing the URL request instead of the URL, the `isEqual:` test passes and the error is properly forwarded to the failure block parameter.
Adding lock around AFHTTPRequestOperation -responseString
Adding lock around AFURLConnectionOperation -responseStringEncoding

Adding check for self.response in AFURLConnectionOperation -responseStringEncoding
Merge pull request #772 from 0xced/fix-uiimageview-nil-url

Compare NSURLRequest rather than NSURL
Fixing warnings caused by implicit property attributes
Ignoring -Wcovered-switch-default in AFHTTPBodyPart -hasBytesAvailable
Merge branch 'master' of github.com:AFNetworking/AFNetworking
Using DISPATCH_QUEUE_CONCURRENT for all calls to dispatch_queue_create for media type processing queues
Use dispatch_once to initialize content-type-specific processing queues

Signed-off-by: Mattt Thompson <m@mattt.me>
Added support for repeated key value pairs through use of NSSet
Merge pull request #778 from Neonkoala/master

Support for repeated key value pairs in URL encoded forms
Stashing merge
Fixed comment typo

Minor typo.
Merge pull request #786 from tewha/patch-9

Fixed comment typo
Replacing #ifdef macro check for Security to _AFNETWORKING_PIN_SSL_CERTIFICATES_
Removing #warning about Security framework
Fixing compiler warnings in SSL pinning initializers

Minor refactoring