Squashed 'bundle/vim-bufferline/' content from commit 1788138

git-subtree-dir: bundle/vim-bufferline
git-subtree-split: 17881383a670e9383a0cdc0fedf2107b2416ec01
Merge commit 'c6ac21f33938e6825a58909f0f85896f8aa21b9e' as 'bundle/vim-bufferline'
Added bufferline plugin