Add admin command 'gerrit show-connections'

This command displays the current connection table within the
SSH daemon, including connection start time, idle time, user
name, IP address, and active command(s) running on that one
connection.  For example,

    Start     Idle   User            Remote Host
--------------------------------------------------------------
 12:21:17 00:00:01  sop             my.laptop.dhcp.example.com
 [ git-upload-pack '/kernel/msm.git' ]

 12:21:19 00:00:00  sop             localhost
 [ gerrit-show-connections ]

--

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