Squashed 'bundle/vim-airline/' content from commit 310331c

git-subtree-dir: bundle/vim-airline
git-subtree-split: 310331cfc45ea1fbec8987042ed94c3740cc7041
Merge commit 'b5a7c79a1e8f62e62eed391036d87a5147fcd119' as 'bundle/vim-airline'