SpecRunner, editor support, and readme tweaks

 * Renamed root to `uproxy-lib-root` so it's easier to tell projects apart in sublime (when you have windows multiple open)  
 * Tweak to README to explain how to generate the common-grunt-rules JS
 * Fixes https://github.com/uProxy/uproxy/issues/474 (SpecRunner naming so Chrome apps don't get broken)

TESTED: 
 * grunt test
FYI, uproxy-networking uses the repo name:
https://github.com/uProxy/uproxy-networking/blob/dev/editor_support/sublime_text/uproxy-networking.sublime-project#L5

I'm fine with this convention too, though.