User registration form. Needs to get wired to rest api.
 Changes to be committed:
	modified:   public/js/directives/login/login.html
	modified:   public/js/directives/login/login.js
	modified:   public/js/directives/nav/nav.html
	modified:   public/js/sos.js
	modified:   public/partials/header.html
	new file:   public/templates/signup.html
	modified:   server/courses/courseModel.js
	modified:   server/users/userModel.js
	modified:   server/users/userRoutes.js