Templates:
- new template edit_visit_type.html
- add edit link to view_project_visit_types.html

decorators.py:
- add permissions check for visit_type_id

models.py:
- better exception handling in Sample.clean(), specifically catch the ValueError if no sample file was uploaded and make sure the file is an FCS file by catching any exception from loadFCS

urls.py:
- add route for edit_visit_type view

views.py:
- new view edit_visit_type()
Templates:
- view_project_panels.html: update with new dictionary based panels structure

models.py:
- added panel description to Panel model

views.py:
- optimize view_project_panels() to avoid large number of DB queries