Initial configuration for running in a production type env on AWS.

- Includes a Dockerrun.aws.json file to tell Elastic Beanstalk how to
  run the app.
- Adjusted the asset pipeline to work correctly in a production
  environment.
- Tweaked the Dockerfile to default to running rails in a production
  environment, and to precompile assets.
- Added test coverage stat to the README.
A working architecture that runs in a production style environment.
Misc JS bugs.
Fixed some bugs, enabled admin & seeds for prod.
Fix joatu api endpoint in JS.
Initial configuration of capistrano for deployments.
Configure database credentails for Capistrano deploys.
Tweak capistrano tasks, stop rails from trying to install postgis.
Remove other "create extension" commands from rails.
Revert "Remove other "create extension" commands from rails."

This reverts commit 286a3f77ae8d92eb670ccd26c4993885e64f988a.
Re-enabling postgis extension in rails.

Testing whether Rails can define the extensions it needs without running into
permission errors, so long as in sensitive environments something else (chef)
installs the required extensions.
Remove out-dated comment from Gemfile.
Configure unicorn .sock and .pid files.
Share assets between deploys, and fix capistrano's unicorn restart task.