Merge pull request #11 from gholt/master

Various Improvements
Added 'mark' command and filtering
Merge pull request #12 from gholt/mark

Added 'mark' command and filtering
Ignore missing username

Apparently this happens sometimes with Gerrit. Maybe the user made a comment and then deleted their account? Not sure.
Merge pull request #13 from gholt/ignore-missing-username

Ignore missing username