Sanity checks against input for ticket search
Sanity checks against input for ticket search

Currently input parameters within the ticket search view are not
validated, thus (manually) altering the parameters in the query string
issues a 500. This patch attempts to solve this problem, reverting to
the default query when the situation can't be recovered.

fjcapdevila/django-helpdesk,mrkiwi-nz/django-helpdesk,gwasser/django-helpdesk,comsnetwork/django-helpdesk,iedparis8/django-helpdesk,rossp/django-helpdesk,iedparis8/django-helpdesk,gjedeer/django-helpdesk-issue-164,rossp/django-helpdesk,harrisonfeng/django-helpdesk,temnoregg/django-helpdesk,django-helpdesk/django-helpdesk,chriscauley/django-helpdesk,django-helpdesk/django-helpdesk,gwasser/django-helpdesk,mrkiwi-nz/django-helpdesk,vladyslav2/django-helpdesk,gjedeer/django-helpdesk-issue-164,gwasser/django-helpdesk,comsnetwork/django-helpdesk,temnoregg/django-helpdesk,chriscauley/django-helpdesk,harrisonfeng/django-helpdesk,vladyslav2/django-helpdesk,chriscauley/django-helpdesk,comsnetwork/django-helpdesk,mrkiwi-nz/django-helpdesk,iedparis8/django-helpdesk,temnoregg/django-helpdesk,fjcapdevila/django-helpdesk,chriscauley/django-helpdesk,rossp/django-helpdesk,gwasser/django-helpdesk,vladyslav2/django-helpdesk,django-helpdesk/django-helpdesk,harrisonfeng/django-helpdesk,fjcapdevila/django-helpdesk,vladyslav2/django-helpdesk,django-helpdesk/django-helpdesk,fjcapdevila/django-helpdesk,gjedeer/django-helpdesk-issue-164,temnoregg/django-helpdesk,mrkiwi-nz/django-helpdesk,rossp/django-helpdesk,harrisonfeng/django-helpdesk,iedparis8/django-helpdesk,comsnetwork/django-helpdesk