BZ #1049633 - Foreman should support VXLAN

https://bugzilla.redhat.com/show_bug.cgi?id=1049633

A couple of the variables inside the compute and networker classes were missing
the 'ovs_' part of the param name.
Merge pull request #125 from jguiditta/vxlan_param_fix

BZ #1049633 - Foreman should support VXLAN