Don't install lua plugin for wireshark 1.12+

Apparently there is a conflict where the lua plugin
conflicts with the built-in dissector for openflow
that is included with 1.12 and up. For now, we will
just not install the plugin. This should fix the
14.10 VM build.

Additionally, I have added a handy function,
version_ge, which compares version numbers in
canonical x.y.z format. Thanks to stackoverflow for
pointing out the incredibly useful sort -V option!