Add app description.
Get item references
Merge remote-tracking branch 'upstream/master'

Conflicts:
	PodioKit/Common/Models/PKTItem.h
	PodioKit/Common/Models/PKTItem.m
New naming convention
Change mapping method for response's body

remove appID in argument replace by mapping in the response
remove NSLog
Merge pull request #7 from RLRunware/master-extended

Fetch application description property and Fetch Item references