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

(cherry picked from commit 27ad1be4a4ee8d0256055122848546041dbd1fc4)
Merge pull request #269 from toabctl/c4-region-support

Use region from keystone settings