tmux.conf: fix for tmux 1.9

tmux.conf

@@ -27,8 +27,8 @@ set -g window-status-format "#I|#W:#T#F"
 set -g automatic-rename on
 
 # disable updating status-left and status-right
-set status-interval 0
-set status-keys emacs
+set -g status-interval 0
+set -g status-keys emacs
 
 set -g message-bg white
 set -g message-fg black