Working with the new AFNetworking lib
Fix the requests to the server
I remove the user and pass for test
Changed the method name for detect a credential error in an upload progress with the new AFNetworking2.0 library: setAuthenticationChallengeBlock per setWillSendRequestForAuthenticationChallengeBlock
Studing how to implement the NSURSession
Merge branch 'develop' into OC-3571_background_uploads
Now we can upload files on background and receive a success
I add the progress value but the bat does not works
Manage the failure response and return it to the ManageUploads
Now I send the ID of the upload and it is different for each upload
Revert "Now I send the ID of the upload and it is different for each upload"

This reverts commit 935043b8caf63a59de4340c5fc104bc4d8ed2c71.
Set only one connection per host in uploads
Add setTaskDidCompleteBlock to get the callbaks of the background process
Add setTaskDidSendBodyDataBlock method in order to get the callbacks of the progress of the NSURLSessionTasks
Add new constant for the uploads sessions, remove unused code and add some comments for the new methods
Update downloads tests with LIFO parameter, add three news unit test for uploads in background and create a UNIT_TEST macro to use a diferent nsurlconfiguration in tests
Remove config data
Example updated with background upload and background fetch events
Remove config data
Merge branch 'develop' into OC-3571_background_uploads