Add skeleton for new OpenStack cloud provider
Add github.com/rackspace/gophercloud package as a dependency.

Note this also pulls in:
github.com/kr/text
github.com/mitchellh/mapstructure
github.com/racker/perigee
github.com/tonnerre/golang-pretty
Read user/pass from config and authenticate to OpenStack
Implement Instances interface for OpenStack cloud provider
Merge pull request #1676 from anguslees/openstack-provider

Add OpenStack cloud provider