Fix Gruntfile.js

Don't know if I'am just not getting nodejs/grunt but hope this helps and that this is not a bug born out of my stupidity.

Browsify did not package modules (from "knockout" to "signals") because of missing path and alias lead to "missing module..." in browser

By the way:
* In addition to that i had to install "emitter" and "indexof" because grunt said they are missing