Fixed django admin bug, added django admin validaiton
Fixed django admin bug, added django admin validaiton

Fixed the bug in the django admin that saved the field with invalid
json. Added a formfield method and Form Field to validate that valid
json is being entered in the django admin before it is saved. Throws
django admin form error for bad json.

thenewguy/django-jsonfield,velfimov/django-jsonfield,bradjasper/django-jsonfield,natgeo/django-jsonfield,kazmiruk/django-jsonfield,hanuprateek/django-jsonfield,rocketrip/django-jsonfield,philippeowagner/django-jsonfield,dmkoch/django-jsonfield,anvil8/django-jsonfield,SpazioDati/django-jsonfield,Natgeoed/django-jsonfield