* del_source/2 can never return an error, so stop expecting one in riak_core_console.erl
* Remove last function clause from both add_source/4 and del_source/2 to avoid infinite loop problem previously identified with add_grant/add_revoke
* Update type specs: user lists are binary(), not string(), and update add_source to reflect loss of the last clause
Update add_source spec to use userlist()