Django Forms integration

[markfinger]

This lib's focus is on solving the UI part of the problem, but in the process we've reimplemented some features that could have been handled by Django's forms. It might be good if the filters accepted a field arg that handled things like name+label declaration, consuming data from the request, validation, errors, etc.

For example

class IndexViewForm(forms.Form):
    str_field = forms.CharField()
    bool_field = forms.BooleanField()

TextFilter(field=IndexViewForm.str_field)
BooleanFilter(field=IndexViewForm.bool_field)

Would probably need to add the form class into the hierarchy somewhere so that it could be bound and wired so that each filter can read field data and cleaned data.