Add a `babs-save` command.

[smeisler]

Summary

Not sure what people think about this, but the basic idea is that babs-save could be a wrapper around

cd ${project_root}/analysis
datalad save -m ${commit_message}
datalad push --to input

Benefit

The last step is probably unintuitive for non-datalad users, but is necessary for changes to code to be propogated to the BABS jobs.

Next steps

[smeisler]

Maybe something like this was already an idea? #59

[tien-tong]

I think #59 is a lot more involved than just wrapping what you suggested. We'll call this babs sync-code