Adding an upgrade-ovs playbook

We would like to upgrade ovs with a playbook.  This playbook aims to
do just that.
Dont rely on rmmod and modprobe

There are too many unnamed dependencies for using rmmod and modprobe to
reload the ovs modules.  Rely on force-reload-kmod to do the teardown
and bringup.
Update version test

Based upon Dustin's suggestion, I am simplifying this version lookup.
Also jinja-izing the version variable.
Update the upgrade-ovs playbook

These changes reflect the tested OVS upgrade process.  Here we add a
new PPA and simplify the number of steps to upgrade OVS.
Remove changes to group_vars for openvswitch

These are not necessary as we are relying on the PPA to handle
versioning.
Merge pull request #206 from craigtracey/upgradeovs

Adding an upgrade-ovs playbook