Merge pull request #126 from derrh/master

Fixes a login issue
Update Mantle dependency to latest 1.5 & fix related Model issues
Merge pull request #127 from nlambson/master

Update Mantle dependency to latest 1.5 & fix related Model issues
Added canvas login and site admin login options
Merge remote-tracking branch 'instructure/CanvasKit/master'

Conflicts:
	CanvasKit/UIKit+CanvasKit/CKILoginViewController.m