Move calypso to desktop-1.3.1 branch, bump version to 1.3.1

Bump version to 1.3.1-beta in prep for release

Bump version to 1.3.0 ahead of tomorrow release, fix electron-prebuil…

…t to 0.36.7 to avoid accidental upgrade. Version 0.36.9 is causing some issues

v1.2.1 - The Holiday Release