to get submodules: git submodule update --init --recursive
to add submodule (mostly for plugins in /bundle): cd ./bundle git submodule add [repo] OR: git submodule add [repo] bundle/reponame
to fix submodules being in a detached HEAD state:
tail -n 1 README.md ...
git submodule foreach -q --recursive 'branch="$(git config -f $toplevel/.gitmodules submodule.$name.branch)"; git checkout $branch'