Add basic rspec tests to ensure catalog compiles

* Add basic rspec tests
* Add required fixtures: mysql, vswitch.
* Fix relationship between Package['dnsmasq'] and
  Package['quantum-dhcp-agent']. RedHat does not have such package and
  catalog compilation would fail on RedHat platforms.
* Restore Ruby 1.8 compatibility by removing trailing comma
  on the final element of hash.

Change-Id: I7cfc2f9b308116fe9c8b7f242f794792be0be678