Squashed '.vim/bundle/airline/' content from commit b45ab38

git-subtree-dir: .vim/bundle/airline
git-subtree-split: b45ab384ee87c3557e2deb342f3e8329416a0bde
Merge commit '3ce5042166cd71ec1fab2b90f6c1e1fcadfdfc29' as '.vim/bundle/airline'
[vim] airline status bar should always show
[vim] added autocommands for .md extension