Enable quantum linuxbridge support for nova

When running nova with quantum on linuxbridge plugin nova compute should
be aware of it to create appropriate interfaces for vms. This patch
sets libvirt_vif_driver and linuxnet_interface_driver in nova.conf.
Expose Kernel Samepage Merging in the UI

Previously you could only modify it with knife (by editing the
nova-config-$PROPOSAL role). Also, use a boolean instead of 0/1.
Merge pull request #166 from tpaszkowski/pull-req-lb-support

Enable quantum linuxbridge support for nova
Merge pull request #169 from saschpe/release/pebbles/master-ksm

Expose Kernel Samepage Merging in the UI
Merge pull request #31 from crowbar/release/pebbles/master

Release/pebbles/master