Check if name or email are present on global level before adding to git locally

[lechner]

Untested, but is it approximately what you had in mind? Thank you!

[anthonyfok]

I think adding the name and email at the local level is a good thing, so I have reservations about merging this PR. What does everyone else think?

[lechner]

@anthonyfok Hi, do you really do that for any of your other Git repos? What if your email address changes?