hide 'send message button if the user is on the blocked list'
block messages from users in the block list
getting users' online states
modify route config
implement toggling of 'block' and 'unblock' buttons using ajax
implement toggling of 'add to favorite' and 'remove from favorite' buttons using ajax
move 'invitation' button in user/show page to a partial
add method 'has_blocked' and 'has_favorited' to user model
add 'send private message' button to a partial in user/show page
Merge branch 'block-private-message'

Conflicts:
	app/views/private_messages/index.html.erb
	config/routes.rb