Adding Handlebars support stub. Depends on grunt-handlebars being installed globally.
Probably needs to point the user to edit the default task.
Suggestion to fix #104
Thanks man for this idea! I'm going to merge your request, but then alter it to work with grunt-contrib instead of grunt-handlebars which I find inferior (not able to use .html extension?) Also yet another package to install when grunt-contrib provides isn't necessary.