[Fix] Fix for iOS 8 to force synchronized requests.

### What's in

We force BasicAuth requests on iOS 8 to be synchronized. It avoids unwanted "Unauthorized" errors.
This fix will be removed when Apple fixes it on his side or if we drop BasicAuth support.
Check it brah:

https://developer.apple.com/LIBRARY/ios/documentation/Cocoa/Reference/Foundation/Classes/NSProcessInfo_Class/index.html#//apple_ref/occ/instm/NSProcessInfo/isOperatingSystemAtLeastVersion: