Adds dist folder.
Refactored TwigHelper into Twig namespace.

* Now using Encase.
* Simplified design, Packager setups up the Twig environment.
* Much more customizable.
* The CliPackager uses this flexibility to setup a Twig Environment for
  compiling templates via the `twig_compile` cli.
Merges branch 'feature/reorganize-twig-helper' into develop