[Merge] lp:~bfiller/upstart/desktop-mode into lp:ubuntu/upstart

[Steve Langasek]

Review: Disapprove

Per discussion on IRC, we should do this differently by having apps detect an existing feature of the X environment (e.g., $DISPLAY being set) instead of setting another variable.
-- 
https://code.launchpad.net/~bfiller/upstart/desktop-mode/+merge/212075
Your team Ubuntu branches is subscribed to branch lp:ubuntu/upstart.