register and login #1 #2
Merge branch 'develop' of https://github.com/liyijie/room_monitor into develop

Conflicts:
	db/migrate/20140516015541_devise_create_users.rb
	db/schema.rb
add login and logout html into the application.html.erb
add user and area many to many relation through AreaRelation
relation bug fix
modify application.html.erb, user can choose the area from the
dropdown-menu.
modify html file