Add interface fallback (Powerline>Unicode>ASCII)
Add interface fallback (Powerline>Unicode>ASCII)

Basically what the title says. First check if the user has Powerline,
fall back to Unicode symbols if he doesn't and fall back to ASCII
symbols if he doesn't have that either.

bling/vim-airline,tschundler/dotfiles,yzhou61/vim-airline,tschundler/dotfiles,HarmtH/vim-airline,unphased/vim-airline,tschundler/dotfiles,rchicoli/vim-airline,chrisbra/vim-airline