support git submodules

[zdzichu]

Hi,

It would be awesome if GD supported git submodules. This way various teams could have repositories with their own databags / cookbooks.
Also, some kind of whitelisting would be useful in that case:

• git submodule -> list of databags or cookbooks allowed to be synchronized from this submodule.

Please consider, thanks.

[jaymzh]

There's a PR open for this, but it's unfinished, and I don't expect the contributor will finish it anytime soon. It's mostly done but has one big bug that has to be tracked down. Want to take a wack at finishing it?

[zdzichu]

OK, I've found facebook/between-meals#18

I won't sign any CLA personally, so I won't be contributing in my free time. I could do it during my workhours, but first our corporate lawyers have to finish the process of vetting the CLA.