Add BlueJeans Link

branches-for-fun-and-profit/README.md

 # Dec 29: Branches for Fun and Profit
 **Thursday 12/29, 9:00am in JICS Auditorium (5100 RM 128)**
+Offsite folks can join us via [BlueJeans](https://bluejeans.com/309751285).
 
 Branching is a central part of any version control system, and git's facilities
 for branching are second to none. In this workshop we will cover: