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