Add support for quantum cisco plugin

Adds support for the cisco networking plugin.
This adds a new required parameter to
site.pp which determines the quantum
plugin to use, and creates the new
quantum::plugins::cisco class in core.pp
if it is set appropriately.

Requires:
https://review.openstack.org/#/c/36830
https://review.openstack.org/#/c/36597
Merge remote-tracking branch 'origin/multi-node' into cisco_plugin_support

Conflicts:
	manifests/core.pp
Merge pull request #101 from michaeltchapman/cisco_plugin_support

Add support for quantum cisco plugin