add project users table
start a basic user invitation page
display all users of all organizations
add local filtering for users list
add user to project
use a transaction when saving new user
abstract user tile to a partial, add user tiles to the project#show page, added #remove_user
change index to uid
ensure you can't repeatedly add the same user to the same project
InvitedUser becomes RegularUser when he auths with GitHub
haml-ified