Changed the configuration loading and API

The new API relies on a global Settings object, which is located under
`hanyuu.settings`.

Settings can be accessed by using the dotted attribute way, so for
example getting the database hostname you would do
`hanyuu.settings.database.host` underlying is a simple dict subclass.

Changed example configuration file to YAML format.
Added streamer example configuration

Also added PyYAML requirement to the setup.py