Create a custom server for each user
Add support for configuring socket group permissions
Don't let client_mode run arbitraty tmux commands

Clients should not have the ability to run arbitrary tmux commands
against another user's tmux sessions.  Running 'wemux kill-server' as
a client will, in fact, destroy another user's session.
Optionally allow the default config directory to be replaced during installation, but fallback on the old behavior if this replacement is not done.
Add per-user ~/.wemux.conf overridable config
Allow clients to run wemux h or wemux help