cli,glusterd: Changes to cli-glusterd communication

Glusterd changes:
With this patch, glusterd creates a socket file in
DATADIR/run/glusterd.socket , and listen on it for cli requests. It
listens for 2 rpc programs on the socket file,
- The glusterd cli rpc program, for all cli commands
- A reduced glusterd handshake program, just for the 'system:: getspec'
  command

The location of the socket file can be changed with the glusterd option
'glusterd-sockfile'.

To retain compatibility with the '--remote-host' cli option, glusterd
also listens for the cli requests on port 24007. But, for the sake of
security, it listens using a reduced cli rpc program on the port. The
reduced rpc program only contains read-only procs used for 'volume
(info|list|status)', 'peer status' and 'system:: getwd' cli commands.

CLI changes:
The gluster cli now uses the glusterd socket file for communicating with
glusterd by default. A new option '--gluster-sock' has been added to
allow specifying the sockfile used to connect. Using the '--remote-host'
option will make cli connect to the given host & port.

Tests changes:
cluster.rc has been modified to make use of socket files and use
different log files for each glusterd.
Some of the tests using cluster.rc have been fixed.

Change-Id: Iaf24bc22f42f8014a5fa300ce37c7fc9b1b92b53
BUG: 980754
Signed-off-by: Kaushal M <kaushal@redhat.com>
Reviewed-on: http://review.gluster.org/5280
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Krishnan Parthasarathi <kparthas@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>