make slide in optional
Merge https://github.com/emiddleton/data-confirm-modal into emiddleton-optional-fade

* https://github.com/emiddleton/data-confirm-modal:
  make slide in optional
Rework @emiddleton's fade option
Whitespace
Merge @emiddleton's optional slide in option. Thanks! cc: @lleirborras

* emiddleton-optional-fade:
  Whitespace
  Rework @emiddleton's fade option
  make slide in optional