Update submodules and add .notebook to ignore

.gitignore

@@ -3,3 +3,4 @@ vim/autoload
 vim/view
 vim/.netrwhist
 vim/tmp/*
+.notebook

vim/bundle/vim-airline

@@ -1 +1 @@
-Subproject commit eb04e25d347c50bc1bf8143f2ada776e39fbc729
+Subproject commit 15666d71e39cd91add74ff6919071d718c098db4