Add support for ForkLift 2 to the ForkLift plugin

The ForkLift plugin now supports ForkLift 2 as well as ForkLift 1.
If ForkLift is not running it also waits for it to be running before
trying to switch to the specified directory

ForkLift 2 was [released in November 2010](http://www.binarynights.com/blog/2010/11/forklift-2-0.html), so most people using the app are probably using that version.