Added GooglePlus iOS SDK
Adjusted project settings for Google Plus.
Added SHKGooglePlus.h/.m
Added basic features for Google Plus
Finished the Google Plus URL/Text sharing.
Added Google Plus settings to the Demo App.
Corrected the implementation for Google Plus.
Handled Google Plus callbacks.
Added instructions in SHKGooglePlus.h.
Fixed some errors for SHKGooglePlus
Merge remote-tracking branch 'upstream/master'

Conflicts:
	ShareKit.xcodeproj/project.pbxproj
Rename the title "Google Plus" to "Google+"
REFACTORING: removed addSkipBackupAttributeToItemAtURL: calls and NSFileManager category

it was used to exclude items saved for offline queue from backup. It is not needed, because offline queue is in CACHE directory, which is not included in backups by default.
REFACTORING: improved SHKItem saving + SHKOfflineSharer uses modern objective-c syntax
REFACTORING: SHKFacebook now uses ShareKit's new builtin routines for saving/restoring the item
Merge branch 'master' into googlePlus

Conflicts:
	ShareKit.xcodeproj/project.pbxproj
Merge commit '06ea747c50cc2c20521e7b38da8f2e9d59c46da4' into googlePlus
removed Google+ graphics and libGooglePlus.a from project, it is not needed
REFACTORING: SHK.m moved to modern syntax, singleton using dispatch_once
BUGFIX: SHKGooglePlus fixed memory leaks and simplified
REFACTORING: removed JSONKit submodule (as iOS4 support is dropped, we no longer need it)
SUBMODULE UPDATE: Facebook iOS sdk 3.2