Support running the SSH daemon from the command line

"java -jar gerrit.war daemon" can now be used to start up only the
SSH daemon portions of Gerrit.  This can be useful if you want to
run only the restricted access server for receive-pack purposes,
or to test or debug the daemon portions of the code base.

Signed-off-by: Shawn O. Pearce <sop@google.com>
3 files changed