Tightened navigation among all screens
Merge branch 'master' of github.com:fnha2000/CS1635BookSharing

Conflicts:
	bin/classes.dex
	bin/classes/cs1635/group/booksharing/BuyActivity$1.class
	bin/classes/cs1635/group/booksharing/BuyActivity.class
	bin/resources.ap_
	src/cs1635/group/booksharing/BuyActivity.java