Five things you need to know today, and the end of a local mystery?

Good morning, Boston. Here are the five things you need to know to start your Friday. A Mass and Cass BID Businesses near Mass and Cass are joining with the Newmarket Business Association to submit paperwork to city officials to create what is known as a "business improvement district" at the intersection of Dorchester, Roxbury and the South End, Greg Ryan reports. Mall site revived in Woburn The former Woburn Mall site, now reborn as Woburn Village, has added a number of high-profile retailers…