Cap Metro-specific changes

Updated configuration and example web app instructions to use Austin
Capital Metro data.
Add contributors to package.json
Added Procfile for use with Foreman/Heroku
Use MONGOHQ_URL environment variable, if present

If the MONGOHQ_URL environment variable is present, then it will be
parsed into hostname, port, database, etc. If username/password
credentials are present, then they will be used to authenticate to the
database.