Reword the help messages
Reword the help messages

Help messages should now be valid with both --own-project and
--cleanup-project mode. Also make this 2 options mutually
exclusive

Change-Id: I54f73b94e1241367763365468a159ef6a329e8ba

remoteur/ospurge,openstack/ospurge,DigitalPacific/ospurge,FlorentFlament/ospurge-packaging,tnahak/ospurge,openstack/ospurge,JonasPf/ospurge,stackforge/ospurge