Altered user_type to be an enum
Fixed the display of "swiper" and "swipee" using User.user_type_str
Merge branch 'master' into implement-enum

Conflicts:
	user/register.html
Updated enum to use buyer and seller
Merge branch 'enum-recent' of https://github.com/SwipeMe/SwipeMe into enum-recent
Fix seller printing as buyer bug.
Revise comments