If I understood it correctly gruvbox has it's own airline and you don't need vim-airline installed. I followed the easy install with Vundle but for some reason the airline just doesn't load. I'm using Konsole as a terminal. Thank you.
Gruvbox is a colorscheme, and comes packaged with an airline theme as can be seen by the inclusion of an autoload/airline/themes/gruvbox.vim file.
Gruvbox itself does not come with airline, but it supports it.
To use airline, you will need to install it; then, you may
let g:airline_theme = 'gruvbox' in your vimrc.