Minor update for Mac: This version includes an update for MacOS 10.11, El Capitan.
Updated from 1.2.1 in that we are reverting back to pyserial 2.5. (Pyserial 2.7 has caused errors for some users on El Capitan that we have not been able to reproduce on our development computers.)
Windows and Linux users are encouraged to use the previous stable release, 1.1.0.