Use Mocha reporters to add information on screen

Hi,

I've been switching the growl + custom info logging to the Mocha defaults reporters. Mocha allow a lot of pretty, usefull and colorfull reporters, I found that this was missing from the Phantomjs/grunt version.

This needed quite a lot of changes, now every Mocha events occuring inside Phantomjs is bubbled to the Grunt runner where we "façade" some Mocha test/suite property/functions in order to make it run through a reporter.

The results are good by my side and it's been working with every reporter I've tested.

Let me know what you think!