Add key bindings for taskwaror 'context' switching

dotfiles/i3/config

 
 bindsym $mod+m              exec "$spn bmo menu status"
 bindsym $mod+Shift+m        exec "i3-dmenu-desktop --dmenu='bmo dmenu'"
+bindsym $mod+o              exec "$spn bmo menu context"
+bindsym $mod+Shift+o        exec "task context none"
 bindsym $mod+p              exec "$spn bmo menu run"
 bindsym $mod+Shift+p        exec "$spn bmo menu run_hist"