SB+SK template project & build scripts

the SpriteBuilder+SK project correctly linked with the SB template project for Sprite Kit

Build distribution script updated to generate (zip) the SK project, and split up to be able to add this as a run script phase (I needed to fix the problem where the template was out of sync with current work unless I re-ran BuildDistribution.sh over and over again).

cleanup, removal of the source files now in the Spritebuilder+SK repository: https://github.com/apportable/SpriteBuilder-SK