Remove database config

[leesmith]

Remove database.yml so people can use their own database settings without having to worry about changes to database.yml.

This might effect your Travis setup. Here's how I tell Travis to configure the database:

https://github.com/leesmith/decent_authentication/blob/master/script/ci/before.sh

The point is, this lets people use their own database settings so they don't have to worry about accidentally checking in a modified database.yml.

[leesmith]

Looks like I've already fallen victim to this: https://github.com/paweljw/bookstore-backend/pull/6/commits/3e5bf84c62113dcd75d8faaaec6584d776efa244

Whoops. 😜