This patch switches the service name from 'Image Service' to
just 'glance' so that it matches what we do for other services.
Typically we use the project (auth) name for the service_name.
Not having a consistent catalog can cause failure to find
endpoints for some services. Mistral for example would fail
to lookup the glance endpoint due to it being set as 'Image Service'
rather than 'glance'.
Change-Id: I17116c0f995ab76ed79bd8b2df57629c1ed4e4d0
Closes-bug: #1584229
44bf1232a5