Update forms.py

fixes button primary issue on submit.
Merge pull request #53 from Tusky/master

Update forms.py
fix for python 3.x incompatibility in pagination
Merge pull request #59 from nsmith448/master

fix for python 3.x incompatibility in pagination
Add extra explanation in forms.py, fix #58
Merge branch 'master' of https://github.com/dyve/django-bootstrap3
Remove async, fix #56
Version bump to 2.5.2 (bug fixes)
Fix required bug in CheckboxSelectMultiple widget