Apply patch to fix "negative" images issue.

Issue #1706: https://github.com/AFNetworking/AFNetworking/issues/1706
Merge branch '1.x' of https://github.com/solydzajs/AFNetworking into 1.x

This brings in patch from Pawels AFNetworking repo - Apply patch to fix "negative" images issue.

Conflicts:
	SANetworking/SAImageRequestOperation.m