SB ARC: fix LabelTTF node not showing the system font list
refactor: replaced appdelegate singleton properties (resource, plugin)

- prevent confusing them as properties/ivars of the appdelegate
- use the singletons the same way throughout app (some code went through appdelegate properties, most used sharedManager singleton accessor as one would expect it to be used)
- removed passing around resource manager to another class (one instance)
SB ARC: fix wrong and superfluous uses of weak/__weak
Merge branch 'develop' of https://github.com/KoboldKit/SpriteBuilder into develop

Conflicts:
	SpriteBuilder/ccBuilder/CCBWarnings.h