Recursive clone/pull

[apertome]

It would be great if this did a recursive clone/pull, this would pull in all the dependencies. This could be the default behavior, or optional.

The perfsonar/toolkit repo's README.md has some examples that could be adapted:
https://github.com/perfsonar/toolkit/blob/master/README.md

Basically,

clone:
git clone --recursive https://github.com/perfsonar/toolkit.git

pull:
git submodule foreach git pull origin master