Merge pull request #94 from jocelynlih/paul

Putting my change back into 1.sks after replacing Ankur's work. This cha...
Added the new Steve sprite to the Art folder (master EPS and properly sized sprites).
Shuffled around the old Steve into his subfolder.
Updated the code to reflect Steve's new 8-frame animation sequence.
Updated Steve's mass in HeroNode.swift to account for his slightly different proportions.
Removed assets that we're not using or reference assets that we didn't create and no longer need.
Merge pull request #95 from jocelynlih/paul

New Steve sprite, asset cleanup
Merge branch 'master' of https://github.com/jocelynlih/SwiftGameBook into paul-newsketch
new changes from master