Add a accounts plugin (accounts class) that defines
variables and methods common to 'users' and 'stageuser'.
accounts is a superclass of users/stageuser
Add the stageuser plugin, with support of stageuser-add verb.
Reviewed By: David Kupka, Martin Basti, Jan Cholasta
https://fedorahosted.org/freeipa/ticket/3813
Reviewed-By: Jan Cholasta <jcholast@redhat.com>
Reviewed-By: David Kupka <dkupka@redhat.com>
