feat($core): adds basic required input implementation
feat($core): makes required label markup as template

The template name is stored in a configuration property on
`AwesomeForm`.
The hints and errors template paths are also now stored in the
configuration.
fix(templates): adds a class on required fields and use condition for partial call
style(awesome_ui): massive updates of the AwesomeUi theme

Includes:

  - new view helpers to generates FontAwesome icons.
  - client widgets to handle many progressive enhancement and
responsive behavior in forms.
  - aliases of `widgets` (`$w`, `widget`).
  - refactoring of sass mixins.
  - a new view to test the themes forms.
  - new input styles.