[AddonManager] Add github support
[AddonManager] Add github support

- Add support for installing macros from https://github.com/FreeCAD/FreeCAD-addons.git.
- Macros which have the same name on git and on the wiki are not
  repeated.

Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master