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
Merge pull request #393 from toabctl/add-region-support

Use region from keystone settings
Add region parameter for CLI usage

Use the custom region name for nova cli usage.

related to: https://bugzilla.novell.com/show_bug.cgi?id=896481
Merge pull request #396 from toabctl/region-for-cli-usage

Add region parameter for CLI usage
Implement support for Nova V2.1 API

Nova V3 API was deprecated in favor for Nova V2.1 API. since
we had it offered only optionally and disabled by default, and
since it is currently completely broken, lets just remove it
alltogether and enable V2.1 API instead, which is going to be
stable going forward.