Update openstack::db::mysql specification

This patch is aim to update the openstack::db::mysql
option specification and the use example.

Fixes bug #1208029

Change-Id: Ia057c1a9529d5b6b9ffa99ebd65cfdff05643081
Merge "Update openstack::db::mysql specification"
Revert provisioning of shared networks.

 * As currently defined, the public network is configured to
   support floating ip assignment, and the private network should
   be private to the tenant.  In neither case should the network
   be configured as shared.

Change-Id: I51f7cd75cfd2b8a5a1aadad45b98dd010c0f1935