Catch glance image create exceptions

Catch exception from glance when image creation fails because the
requested name is too long. Currently the exception is not caught
in the api which results in an 400 Bad Request correctly being
returned, but also leaving a traceback in the logs. Correctly catching
the exception and explicitly raising an HTTPBadRequest removes
the production of the traceback.

Fixes bug #1169560

Change-Id: I511da79cb0b1b4578bf43f0819b2ac64fb6e5fb3
Merge "Catch glance image create exceptions"