Improve Growl message for failed tests

Growl enough information to allow debugging of simple failures based solely on the information provided by Growl.

Specifically, instead of the traditional notification like

    Title: Failed

    1 of 40 tests failed

display a more detailed notification like

    Title: 1 of 40 tests failed

    Session should monitor the added projects and issue reload requests

    session.js:40

    ReferenceError: foo is not defined

This is a very simple patch; didn't try to make it an option or something. I welcome your suggestions.