Sync multiple git repos for submodules #30
Description
When working on a project that has submodules or other git repos within the workspace, sometimes it would help to sync them all.
We already iterate through and show all repos in the pick list, so perhaps we make it into a multi-select; these would then all be sent over the wire and each repo can then be sync'd. If a sync error occurs in one repo (e.g. dirty commit), then the others should still be sync'd.
This may require #31 otherwise we will have to re-select the submodule each time you run the sync command... unless prhaps we do it the cheap way and only re-check selections where the repo exists in the workspace.