Add docker-api to Gemfile
Add language model
Replace evaluation job with one that uses docker

Also update various models to reflect new evaluation format.
Delete all old evaluator stuff
Make db:seed insert all the fixture languages into the DB
Add support for memory limit

Right now it seems the submission will just time out if it tries to
allocate too much memory
Merge pull request #9 from Sirupsen/docker-evaluation

Docker evaluation