Update .tmux.conf with new formatting option.
Update .tmux.conf with new formatting option.

Tmux updated the way background and forground color
settings are set in version 2.9. The new format uses -style options.
pane-active-border-style fg=blue instead of pane-active-border-fg=blue

mikerathbun/dotfiles,mikerathbun/dotfiles,mikerathbun/dotfiles,mikerathbun/dotfiles