Remove try/catch
Revert "Remove try/catch"

This reverts commit c239e15ce51cd725e6645f519f0c759debc7b9fc.
Merge branch 'master' of git://github.com/AFNetworking/AFNetworking
Don't update NSProgress for data tasks

1. Progress is never returned by data task methods, only download methods. Those methods update the progress elsewhere so removing this shouldn't affect them.
2. The totalUnitCount is never being set during data tasks, so even if it was being returned, the NSProgress always reports a fractionCompleted of 0 right now.
3. There is a crash that occurs here rarely. My best guess is that the delegate is still being sent messages as it's being released.
Merge branch 'master' of github.com:PadraigK/AFNetworking into PadraigK-master
Merge branch 'master' of git://github.com/AFNetworking/AFNetworking
UIKit requires that the completionHandler for application:handleEventsForBackgroundURLSession:completionHandler be called on the main thread.

http://developer.apple.com/library/etc/redirect/xcode/ios/889e4b/documentation/Foundation/Reference/NSURLSessionDelegate_protocol/Reference/Reference.html
Merge branch 'master' of github.com:PadraigK/AFNetworking
Merge branch 'PadraigK-master'
Merge branch 'master' of github.com:AFNetworking/AFNetworking
Removing #import <AssertMacros.h>
Squashed commit of the following:

commit b71139c2bca91b8610f2a373df85c3a8a161585c
Author: Mattt Thompson <m@mattt.me>
Date:   Wed Jun 11 12:44:53 2014 -0700

    Separating session subspec from connection subspec

commit b39dac5ed9fbe120dc4d27c73fd742513dc15796
Author: Mattt Thompson <m@mattt.me>
Date:   Wed Jun 11 12:41:12 2014 -0700

    Splitting AFNetworkingErrorDomain into AFURLRequestSerializationErrorDomain and AFURLResponseSerializationErrorDomain

commit b8a31216df7c4b8674f1795dfaf6fb4438a451c5
Merge: 0ec17bd d5e2295
Author: Mattt Thompson <m@mattt.me>
Date:   Wed Jun 11 12:11:24 2014 -0700

    Merge branch 'serialization-stands-alone' of github.com:nolanw/AFNetworking into nolanw-serialization-stands-alone

commit d5e229540c45632fcdaee3069864c1e2d7a97de4
Author: Nolan Waite <nolan@nolanw.ca>
Date:   Wed Jun 4 18:30:56 2014 -0300

    Move string constants used by Serialization subspec into Serialization subspec

    Arbitrarily picked AFURLRequestSerialization.[hm] even though AFNetworkingOperationFailingURLResponseErrorKey probably fits better in AFURLResponseSerialization.[hm]
Merge branch 'master' of github.com:AFNetworking/AFNetworking