Add management of unauthorized keystone exceptions

  * Raise InvalidEnpointsException if the endpoint properties are wrong
  * Raise InvalidAdminException if the user is not admin
  * Print a specific message to the user if they are in this case
  * Remove the stacktrace if the user encounter a InvalidArgumentException

Change-Id: I4659795924de57de1a58cec42f0d58c34b81c661
Closes-Bug: #1270209
Merge "Add management of unauthorized keystone exceptions"