Use region from keystone settings

The keystone barclamp got the possibility to set a custom region
name. This name must be used by other barclamps as well.

related to: https://bugzilla.novell.com/show_bug.cgi?id=896481



There is still one missing part - deleting the old endpoint if the region name changes. But that seems to be a bit more complicated and at least the function "prettytable_to_array" seems to be broken. So for now Just add another endpoint if the region name changes.