Switch emc config ownership

As suggested at
https://github.com/SUSE-Cloud/barclamp-cinder/pull/1#discussion-diff-14992181
i have switched owner and group for the emc volume type config file.
Merge pull request #198 from tboerger/feature/emc-owner-fix

Switch emc config ownership
Add Multi Backend support

This is based on previous work by Sascha and with help from
Balazs and Thomas.