Vim: fuzzy-find files in specific directories

[gabebw]

https://github.com/christoomey/dotfiles/blob/ea34518fa4d6a03d26d09998fa4486815a2305c0/vim/rcplugins/fzf#L13-L19

nnoremap <leader>ga :Files app/<cr>
nnoremap <leader>gm :Files app/models/<cr>
nnoremap <leader>gv :Files app/views/<cr>
nnoremap <leader>gc :Files app/controllers/<cr>
nnoremap <leader>gy :Files app/assets/stylesheets/<cr>
nnoremap <leader>gj :Files app/assets/javascripts/<cr>
nnoremap <leader>gs :Files spec/<cr>