Remove NonARC folder.

- Move `KWMessagePattern` from `NonARC/` to `Classes/Core/`.
- Remove NonARC directory.
Prevent premature release of invocation arguments.

`-[NSInvocation getArgument:]` is only safe when used with object
ownership of `__unsafe_unretained`. For details
see: http://stackoverflow.com/q/8672675/679254

- Add functional tests which demonstrate premature deallocation
- Convert object ownership to `__unsafe_unretained`
Remove ARC, NonARC subspecs.

Entire project now uses ARC.