Enhancement: Removing dependancy that matter only in theme

[arthur-wsw]

I think floppyforms and django-crispy-forms has no need to be directly integrated in django-admin2 core as they can easily be set on project level. It should simplify maintaining django-admin2 and let more flexibility to final user in the choices of the app used for rendering forms.

I'm not saying whe should not care about django-admin2 compatibility with these app. I think we should also write part in documentation on how user could have them work in there projects.

What are you thinking of this ?

I will made some PR in this way, feel free to integrate them or not.

[galuszkak]

@arthur-wsw it's related to #343 👍

[arthur-wsw]

OK so i will work on this for a future PR