JS Integration tests

@sdreher cc @thraxil This pull request adds a couple of integration tests to DMT using CasperJS and [django-casper](https://github.com/dobarkod/django-casper).

`casperjs` and `phantomjs` are required to run these tests with `make test`.

On OS X:

    $ brew install casperjs --devel

Or anything that has npm:

    $ npm install -g casperjs

http://docs.casperjs.org/en/latest/installation.html


I've also removed some old lettuce-related files.