Tmux: Major overhaul for light version

* Enable aggressive-resize
* Display windows:pane number in the left status window.
* Change the flashy right size elements to lighter colors for eye
  friendly.
* Set window status separator to dotted pipe character. 

Signed-off-by: Ratheesh S <ratheesh@mistralsolutions.com>
Tested-by: Ratheesh S <ratheesh@mistralsolutions.com>