Fix crash if tap outside popover of UIActionSheet dismisses it without selection. If presented from a UIBarButtonItem and a tap away dismisses the sheet's popover, the buttonIndex is -1 causing an index out of bounds exception.
Merge in changes from Jiva's master repo

Bring our fork up-to-date
Use concrete type in itemWithLabel instead of id

If something else in a project has an object with a label property and that class is ahead of RIButton in the imports, the compiler gives a warning that setLabel: is possibly receiving the wrong type.

Switching to the concrete RIButtonItem type clears this warning. There should be no adverse impact that I'm aware of.
Merge pull request #22 from martiancraft/master

Use concrete type in itemWithLabel instead of id
Merge pull request #20 from p-l/master

Added shortcut to create RIButton with both label and action
Renamed 'action' property to actionBlock

Also migrated to implicite synthesize
Added example project