No keystone Endpoint now gives a valid Error Message
No keystone Endpoint now gives a valid Error Message

When no valid keystone endpoint exist, EndpointNotFound exception
is raised with an error message

Change-Id: I75b00cb73b18bc19261c061e0ae217ef251f8853
Closes-Bug: #1208991

klmitch/python-keystoneclient,klmitch/python-keystoneclient