Separate local storage of player data and S3 storage

In order to be able to merge the gga fork back into the main TW repo, there are now two different modes to run the app to keep it compatible with TW Australia's requirements:

1. The default way stores the player data in a local JSON file. This is the recommended mode for running the application in a LAN for development purposes or when there's no decent internet access. This mode will be the default if you start the application via 
``` npm start ``` or
``` node server.js ```

2. The other mode stores the player data on S3, so you will need to include an aws.json file with S3 credentials in the root of the project. (ThoughtWorkers - there is one you can use on the jetpets myTW page). This mode will be activated if you start the application via ``` node server.js --NODE_ENV=heroku ```