Fixing compiler warnings

After upgrading to Xcode 5 and iOS 7.0 SDK, I got a compiler warning on line 95 and 160. Had to cast to (CGBitmapInfo) for the warning to go away.
Removed warning of unused variable (offset)

`RNGridMenu`'s method `-(void)layoutAsGrid` had an unused variable (`NSInteger offset = 0`) that was not used in the method. This causes a warning under many configurations.
Use new screenshot api for iOS 7, which is more efficiency.

* Old api will cause black UIToolbar when rendering
Merge remote-tracking branch 'coryalder/patch-1'
Merge remote-tracking branch 'yuppielabel/patch-1'