Issue 2602: Add support for git to upload.py; by Evan Martin.
Issue 2602: Add support for git to upload.py; by Evan Martin.

nicko96/Chrome-Infra,nicko96/Chrome-Infra,nicko96/Chrome-Infra,nicko96/Chrome-Infra,riannucci/rietveldv2,nicko96/Chrome-Infra,riannucci/rietveldv2