Don't blow up if INSTALLED_APPS is a tuple
Don't blow up if INSTALLED_APPS is a tuple

Since r17158 in Django trunk, INSTALLED_APPS is now not always co-erced to
a list. In my projects I prefer to have INSTALLED_APPS as a tuple as it
reinforces that it is not modifiable at runtime. However, this blows up
in the VersionDebugPanel as it currently assumes it is a list.

Signed-off-by: Chris Lamb <29e6d179a8d73471df7861382db6dd7e64138033@debian.org>

sidja/django-debug-toolbar,ChristosChristofidis/django-debug-toolbar,calvinpy/django-debug-toolbar,barseghyanartur/django-debug-toolbar,seperman/django-debug-toolbar,jazzband/django-debug-toolbar,jazzband/django-debug-toolbar,jazzband/django-debug-toolbar,django-debug-toolbar/django-debug-toolbar,megcunningham/django-debug-toolbar,stored/django-debug-toolbar,calvinpy/django-debug-toolbar,sidja/django-debug-toolbar,spookylukey/django-debug-toolbar,peap/django-debug-toolbar,tim-schilling/django-debug-toolbar,seperman/django-debug-toolbar,django-debug-toolbar/django-debug-toolbar,stored/django-debug-toolbar,megcunningham/django-debug-toolbar,seperman/django-debug-toolbar,pevzi/django-debug-toolbar,tim-schilling/django-debug-toolbar,Endika/django-debug-toolbar,django-debug-toolbar/django-debug-toolbar,sidja/django-debug-toolbar,ChristosChristofidis/django-debug-toolbar,ivelum/django-debug-toolbar,ChristosChristofidis/django-debug-toolbar,pevzi/django-debug-toolbar,Endika/django-debug-toolbar,barseghyanartur/django-debug-toolbar,spookylukey/django-debug-toolbar,ivelum/django-debug-toolbar,spookylukey/django-debug-toolbar,stored/django-debug-toolbar,guilhermetavares/django-debug-toolbar,peap/django-debug-toolbar,guilhermetavares/django-debug-toolbar,ivelum/django-debug-toolbar,peap/django-debug-toolbar,calvinpy/django-debug-toolbar,megcunningham/django-debug-toolbar,barseghyanartur/django-debug-toolbar,pevzi/django-debug-toolbar,tim-schilling/django-debug-toolbar,Endika/django-debug-toolbar,guilhermetavares/django-debug-toolbar