CC-4910: Need to properly handle non-200 http status codes in api client

-wrap all service calls in exception
CC-4897: XSS exploit on library page
Merge branch '2.3.x' of dev.sourcefabric.org:airtime into 2.3.x
CC-4897: XSS exploit on library page

-fixed where this was happening on Calendar - show content
CC-4897: XSS exploit on library page
CC-4910: Need to properly handle non-200 http status codes in api client

-fixed
Merge branch '2.3.x' of dev.sourcefabric.org:airtime into 2.3.x
CC-4913: System -> Media Folder: Exception happens when media folder's path contains '<'
Merge branch '2.3.x' into 2.3.x-saas

Conflicts:
	airtime_mvc/application/controllers/PreferenceController.php