Additional feature: mass commit

[anamariaelek]

Hi, first of all, thanks for putting together these scripts, I find them more useful than the official Classroom Assistant.

However, I found that I needed some more flexibility when evaluating students' submissions - these can be pretty lengthy and consist of several separate parts, so for example, if one wants to grade them part-wise, it only makes sense to be able to commit more than just once before pushing changes to remote. I hope I'm getting my point across well enough :)

With this in mind, I separated the original push_all.sh into commit-all.sh and push_all.sh. I also included the if-else check for whether a directory contains non-git repos and files, which are then skipped - this is useful to me because I want to keep test files and results statistics in the same directory. Lastly, I added the option to use a remote different than origin when pushing changes, although this is not likely to be used very often.

If you think these changes could be useful, I will create a pull request.

Cheers, Anamaria