i like to use the tmux window-style and window-active-style feature to change the background color depending on the fact if a tmux-window is active.
```
set -g window-style 'fg=colour247,bg=colour236'
set -g window-active-style 'fg=colour250,bg=black'
```
These options are not recognized with tmux-2.0.
I tried to follow the instructions from this answer https://stackoverflow.com/a/25952511/4021204 and was able to install tmux-next. when i aliased tmux to tmux-next, tmux-next wasn't recognizing my .tmux.conf file.
So how can i update to tmux-2.1 on Ubuntu 15.10?