Add OpenStack provider support
Merge pull request #122 from detiber/openstackProvider

Add OpenStack provider
Added warning about missing image names when building
Merge pull request #123 from soltysh/cli_fix

Added warning about missing image names when building
Add other OS options

- Rename centos os option to centos6
- Add rhel6 os option
Update README for openstack creds file
Merge pull request #124 from detiber/UpdateREADME

Update README for openstack creds file
Merge pull request #121 from detiber/addOS

Add other OS options