mailmotor: redirect to the correct tab after linking CM account/error
Mailmotor: disable the client dropdown in settings if a client is linked.
By doing this we prevent that people have access to all the clients from the linked account.
mailmotor: remove all data when unlinking the campaign monitor account
mailmotor: added a warning that your data will be removed if you unlink the CM account
mailmotor: added a help text on how to change the client
mailmotor: get the campaign monitor object form the helper class
mailmotor: removed the legacy link_account ajax action