Fix a problem with the construction for initial fields for "multi-fields"
Fix a problem with the construction for initial fields for "multi-fields"

if the field is SELECT_MULTIPLE or CHECKBOX_MULTIPLE the initial values should be split and striped in order to match. Django only allows lists for this widgets.
PEP8 format: 2 lines cleaned

frontendr/django-forms-builder,GetHappie/django-forms-builder,stephenmcd/django-forms-builder,bichocj/django-forms-builder,iddqd1/django-forms-builder,vinnyrose/django-forms-builder,frontendr/django-forms-builder,ixc/django-forms-builder,bichocj/django-forms-builder,GetHappie/django-forms-builder,ixc/django-forms-builder,nimbis/django-forms-builder,vinnyrose/django-forms-builder,simas/django-forms-builder,Afnarel/django-forms-builder,Afnarel/django-forms-builder,nimbis/django-forms-builder,simas/django-forms-builder,stephenmcd/django-forms-builder,iddqd1/django-forms-builder,JostCrow/django-forms-builder,JostCrow/django-forms-builder