Move database.yml to database.example.yml.

  - Remove config/database.example.yml, as it isn't a good example
    config; the file is a stock sqlite3 config file and we're using
    postgres.
  - Move config/database.yml out of the repo, mainly because it
    specifies a database user most people won't have defined.  Use it
    as our new example config.
Merge pull request #23 from kgf/remove-database-yml

Move database.yml to database.example.yml.
We'll want to re-visit this and change the remaining config items to environment vars.

But that's a new ticket.....