New change notification was not being sent for changes created by
the ChangeInserter. I.e. changes created by using the revert and
cherry pick buttons on the Web UI.
Update the ChangeInserter to send notification email to reviewers
for new changes.
Allow the caller to set extra CC recipients, or suppress sending
of emails.
Remove the new change email notification sending from ReceiveCommits
as this is now handled by the ChangeInserter.
Change-Id: I849fa533c17c7b4d3b7688832584490c942c76ba
41b51ccd9c