Allow ovs_enable_tunneling to be Passed Through

Previously, the openstack::compute class did not pass the
ovs_enable_tunneling parameter.  Now that the module supports
Provider Networking, ovs_enable_tunneling must be configurable
to allow users to disable tunneling when using VLAN networking.

Adds parameter ovs_enable_tunneling, which defaults to true.

Change-Id: I73d659d5857b71448e5d5d0ddc65fa79ce8f1d95
Disable dhcp on the provisioned public subnet.

 * Only floating ips are allocated on the public subnet, so
   dhcp is not required.

Change-Id: Id56bf76e39e6c35c01997b19465fc7306442e50a
Merge "Allow ovs_enable_tunneling to be Passed Through"
Removes Unneeded ovs_local_ip Error Message

Previously, the openstack::quantum class would give an error
message when enable_ovs_agent was true and no local_ip was set.

The error has been removed since it is handled by the Quantum
module.

Change-Id: I4ba9c48b44b3733b44b7ba9c7e863ca74892feb5