scan_list_scans.py: change customer_id to None from 0, improve exception to include the URL
scan_list_scans.py: change customer_id to None from 0, improve exception to include the URL

armab/st2contrib,StackStorm/st2contrib,tonybaloney/st2contrib,pidah/st2contrib,tonybaloney/st2contrib,pidah/st2contrib,StackStorm/st2contrib,StackStorm/st2contrib,pearsontechnology/st2contrib,pearsontechnology/st2contrib,tonybaloney/st2contrib,armab/st2contrib,armab/st2contrib,pearsontechnology/st2contrib,pearsontechnology/st2contrib,pidah/st2contrib