fix files attaching to emails for remote storages
fix files attaching to emails for remote storages

Storages like S3, Dropbox, etc have no filefield.path() method - so
submitting ticket with attachment leads to exception

django-helpdesk/django-helpdesk,rossp/django-helpdesk,rossp/django-helpdesk,gwasser/django-helpdesk,gwasser/django-helpdesk,gwasser/django-helpdesk,django-helpdesk/django-helpdesk,rossp/django-helpdesk,gwasser/django-helpdesk,django-helpdesk/django-helpdesk,rossp/django-helpdesk,django-helpdesk/django-helpdesk