Refactored time stamping of models into callbacks
Model: extend ActiveModel::Naming

It seems that worked either way. I have no idea why that is, but the
documentation says this module should be extended.
Documentation: Added docs for callbacks
README: Added section for callbacks
Docs: Never ever hash passwords!
Collection: Renamed `replace` to `update`
Callbacks: Execute validate callbacks before :save, :create, :update
Callbacks: Name the `delete` callbacks `delete` not `destroy`
I consider this to be a troll