jsongCMU

> I'm wondering right now if this might more appropriately targeted to the multi-laser branch or if I can make a new multi-robot branch for this work to live in....

 Pose graph color varies for each robot (node and edge colors). Edges between pose graphs of different robots are solid red. Colors are assigned randomly; tested with 6 robots,...

Updated README with info on Multi-Robot SLAM + GIF

Synchronous and asynchornous SLAM are working. Localization and life long mapping are still TODO's. Currently overwhelmed with other things, so was going to resume PR around June