adding grunt-angular-templates to the build tasks

Hello everyone,

The package 'grunt-angular-templates' could be a great task to add to the build process. 
It concatenates all html templates and registers them in the templateCache, which proves to be a massive performance improvement (no more need to request html partials when needed).

More info here:
- https://npmjs.org/package/grunt-angular-templates
- https://github.com/ericclemmons/grunt-angular-templates

I am not very confident about my implementation, but it is working fine on my end, so I still open the PR.