Create mrgURLScan.py

Creates a new DB of URLs taken from the header checks DB created by mrg.py/mergeSQLDB.py.

From new DB (toBeProcessed), takes each URL in sequence and uses the requests module to 'visit' the page, logging AA's response to a third DB (processed).

Visited URLs are removed from 'toBeProcessed' as they are visited in case the program hangs needs to be restarted.