Gerrit can only accept file comments over HTTP, not SSH. So add
the ability to report over HTTP. This is optional; if no HTTP
credentials are provided, the SSH mechanism will be used for now
and no file comments will be left.
Note, this change does not include the driver API change needed
to sumpport file comments.
This change includes a significant amount of ASL2 licensed code
from Gertty.
Change-Id: I851c62088f228de21441dbd86bf60722d82f94f8
James E. Blair