This reverts commit e1cc6644.

* Preliminary refactoring.

* Refactor to use AFError.

* Update inline docs in SessionDelegate.

* Update AFError implementation.

* Start trying to fix tests.

* Update and fix tests.

* Address comments.

* Remove unnecessary @testable declarations.

* Cleanup whitespace.

Original Commit Log:

* Get build working on beta 6.
* Fix tests.
* Remove team.
* Clean up whitespace.
* Mark as private instead of fileprivate.
* Get rid of intermediate value.
* Open up the classes.
* Remove extraneous set of parens.
* Refactor some casts, remove most uses of AnyObject, properly encode Bool.
* Add bytesReceived variable.
* Make casts optional.
* Cleanup whitespace.
* Replaced optional CFString cast with non-optional variant.
* Removed unnecessary cast for parameters in ResponseTests.

Update MultipartFormData.swift - fix parameter: withN -> withName

Update podspec to 4.0.0, update deployment targets.

Feature - Moving SessionDelegate to Store Requests

fix append overload parameter name withN -> withName

Refactored All APIs for Swift 3

Also removed all cases of `Foundation.` prefixes where possible by refactoring all local variables to avoid naming collisions.