adding isConnectionRequired check for CELL

Reachability can return "ReachableViaWWAN" even in cases such as airplane mode is on. In case of ReachableViaWWAN connectionRequired flag should be checked.

see:
http://stackoverflow.com/questions/19949665/reachability-responding-with-wrong-status-code-in-ios-7-iphone-5
http://forums.macrumors.com/showthread.php?t=942439