unity: add support for utopic

Uh. Interesting..... This looks race-prone though... what if `launchpanelservices` starts before `unity` had time to create whatever resource (file, socket, whatever_upstart_magic...) needed?

Can be tested with something like:
`(sleep 5; echo ok; PATH="$PATH":/sbin /usr/bin/unity) &`

Then we should probably sleep until the resource is ready.