Disable Tranquility when toggling iTerm2

I wasn’t really sure what I was doing; just hacked for 20 minutes until
I got something working. I’m still not keen on the fade; it flickers and
blinds you a bit, so you have to remember to shut your eyes before
toggling iTerm2.
Merge pull request #13 from jezen/master

Disable Tranquility when toggling iTerm2