Set the git author/committer via environment variables (#344)
Set the git author/committer via environment variables (#344)

This eliminates the external dependency that git be configured with a
name and email value, which is required when git merges branches.

Something un-set the global config values for the SYSTEM account
on the Windows workers, and doing this is easier and more reliable.

Signed-off-by: Scott K Logan <8c724d14625be4be480086a9212b212477a303ef@cottsay.net>
ros2/ci,ros2/ci,ros2/ci