SGit shouldn't allow empty ident (missing username and email)

[kankaristo]

I made a small commit with SGit about a week ago, and noticed today that the commit didn't have a username or email.

This breaks some Git commands, which give an error about an "empty ident". This essentially broke our repository, requiring modifications to the repository's history.

To fix it, I used this script: https://help.github.com/articles/changing-author-info

Git normally doesn't allow committing without a username and email; SGit shouldn't allow it either.