Initial implementation of summon and setmirrored

The host has the option of:
`wemux summon` to summon all mirrored clients to his session.
`wemux summon_all` to summon all clients to his session.
`wemux setmirrored` to set all clients to his session in mirror mode.
Add setmirrored and togglemirrored host functions.

`wemux setmirrored` sets all connected clients to mirror mode, watching
the host.
`wemux togglemirrored` toggles all mirrored clients to pair, all pair
clients to mirror.
Prepare for new release.

Synchronize the readme and man page.
Prepare the codebase for new brew version.
Show users on all servers, not just current server.
Disable send when pair/rogue modes are disabled.

Check if rogue or pair mode are enabled before allowing the tmux send
command through. "Security".
Document 'join' with no argument

Join with no argument simply displays the current wemux server, if you're into that.

    $ wemux join
    Current wemux server: wemux
Merge branch 'master' into summon

Let me know if summoning is your bag or not!

Conflicts:
	wemux
Merge pull request #38 from zolrath/summon

It's time!