Allow overriding caching engine with REDIS_URL env variables
Add extra configuration for buildpack
Add instructions for heroku use
Move `database.php.default` to `database.php`

This move allows developers to setup their applications *much* more quickly. A single clone of the repository should be enough to get the database connected, as opposed to a further command after project creation.

This change is made possible because the `database.php` can now retrieve it's configuration from an environment variable, which makes deployment to many environments much easier.
Move environment helper methods to allow usage further up in the dispatch cycle
Allow configuration of Security salt and cipherSeed from environment variables