Update README.md to refer to StackForge
Update README.md to refer to StackForge

* Remove reference to Travis CI
* Update reference to openstack Puppet module
* Add note about supported OpenStack versions

Fixes: bug #1165069
Change-Id: I2aa6375191a7e90e303ff2dee837cbb302c2d1f8

mattymo/puppet-cinder,blkperl/puppet-cinder,TelekomCloud/puppet-cinder,danehans/puppet-cinder,varunarya10/puppet-cinder,mjeanson/puppet-cinder,jeffrey4l/puppet-cinder,gwdg/puppet-cinder,aquto/puppet-cinder,aimonb/puppet-cinder,umago/puppet-cinder,bodepd/puppet-cinder