Make Heroku-Deployable

See the https://github.com/NetLogo/Galapagos/tree/heroku branch for more information. Galapagos isn't too far away from being deployable on Heroku. The things that are missing:

• Pluggable configuration for the play cache - EHCache is used by default, but that's a poor choice for Heroku (not too difficult)
• Make create-standalone requests read the file from disk instead of via a circular request to the server (not difficult)
• Akka actor work (difficult)
• Debug various problems like why the TeamAssembly model won't compile (????)

The value this would add is giving us the ability to stick a deploy to Heroku button on a page for interested parties to look at. Additionally, we could move off of Linode. However, since running the server will require one background worker at minimum, anyone who wanted to run their own server would incur a ~ $35/month charge.

Start with the heroku branch linked in the issue and review its current deployment setup. Investigate the listed blockers in order: pluggable play-cache configuration, create-standalone file access, Akka actor work, and the TeamAssembly compilation problem. Done means Galapagos can deploy and run on Heroku, including the required background worker.