mcc can now set memcached debug mode and has help

mcc can now set memcached debug mode and has help

This patch let us set the debug mode on the memcached connection. Simply
pass --debug as an argument.  I have also added basic usage
documentation with --help, listing the interacting commands as well.

Example output:

$ php mcc.php --help
Usage:
	mcc.php [--debug]
	mcc.php --help

MemCached Command (mcc) is an interactive command tool that let you
interact
with the MediaWiki memcached cache.

Options:
	--debug Set debug mode on the memcached connection.
	--help  This help screen.

Interactive commands:
	get    : grabs something
	getsock: lists sockets
	set    : changes something
	delete : deletes something
	history: show command line history
	server : show current memcached server
	dumpmcc: shows the whole thing
	exit   : exit mcc
	quit   : exit mcc
	help   : help about a command

$

Change-Id: Ib4603eecbd6a8e6f3ba8bf3cf350c0e3df652d3b