Add list all mentors property to organization entity.
Add list all mentors property to organization entity.

This property will allow organization admins to list all the mentors
to assign a mentor to the proposal.

--HG--
extra : rebase_source : d19879e5750ef759bcc1bd52f570eee805fef2cf

rhyolight/nupic.son,rhyolight/nupic.son,rhyolight/nupic.son