Fuel Library puppet rspec testing

We should use rspec testing (rake spec). All the community modules come with appropriate rspec tests that can be used in our CI process ( http://rspec-puppet.com/setup/ )

An example of rake spec testing:

# cd puppet-glance
# rake spec
Finished in 24.65 seconds
216 examples, 0 failures

As for our own modules, we should write rspecs for them.

Also we should implement rspec testing for specific resources (regression testing) in 'openstack' module. Those tests should check that needed (nova/cinder/keystone/glance)_config resources have needed values in the puppet catalog. Since we're not going to sync 'openstack' module with the upstream, such tests will remain intact until we change them, and they won't be affected by other modules sync/merge (keystone, cinder, nova, etc).

Gerrit topic: https://review.openstack.org/#q,topic:bp/fuel-library-rspec-testing,n,z

Addressed by: https://review.openstack.org/137334
    Unit tests script for fuel-library

Addressed by: https://review.openstack.org/140799
    Implement regression rspec tests (WIP)

Work items:
Write new script for per-module unit tests: DONE
Create jenkins job to run rspec testing on commits to fuel-library: DONE