Restoring AWS Elastic Beanstalk deployment.

This commit, after much more twiddling around then I expected, restores
the ability to deploy Lenticular onto the AWS Elastic Beanstalk.  Three
environment variables need to be set on the environment configuration:

    NODE_ENV
    ELASTICACHE_ENDPOINT
    LOCAL_BASE_URL

You will need to restart the application servers after these are set for
the first time; other than that, the contents of the .ebextensions directory
should take care of all of the other necessary configurations.