Classifiche: sanitize input values for regioni/cluster

[verganis]

Da' internal server error visitando
/classifiche/search?territorio_id=4511&selected_year=2012&selected_par_type=entrate&selected_parameter_id=4223&selected_regioni=5630%252C6901%252C7035%252C6079%252C4250%252C3785%252C5246%252C4010%252C1293%252C5001%252C5940%252C2%252C6636%252C7850%252C7450%252C4608%252C2852%252C4906%252C1217%252C3196&selected_cluster=6%252C3%252C8%252C4%252C7%252C5%252C2%252C1%252C9',

File "/home/open_bilanci/bilanci_project/bilanci/views.py", line 2343, in get
selected_regioni_names = Territorio.objects.filter(pk__in=selected_regioni).values_list('denominazione',