Support submodule init and update. Possible values are: `yes` (default), `no`, `on-demand` Example: ``` repository: "https://github.com/username/project.git" recurse_submodules: "on-demand" ``` For some details see this [blog-post](http://hedgehogshiatus.com/git-submodules-automatic-init-and-update-on-f-69372)