MDL-49817 grunt: make shifter work watch on right place
MDL-49817 grunt: make shifter work watch on right place

We mess around with the cwd to find a shifter path, not ideal but avoids
having to refactor the shifter task.

Also fix jshint errors..

1) The gruntfile runs in a nodejs environment and not a browser
environment.

2) There was an uninitialised variable

dilawar/moodle