major re-write


 * allow to receive a level instance instead of creating it
 * always instantiate `Model`'s when it gets values from the database
 * implement `Model.get.all` (returns a stream) and `Model.remove.all` (removes using a stream).
 * implement tests (with coverage)
 * increment docs
 * rename to a comply to level naming conventions

I would also like to apply to help maintain so that I don't keep my fork :)