add virtualenv extension

autoload/airline/extensions/virtualenv.vim

@@ -0,0 +1,13 @@
+" MIT License. Copyright (c) 2013 Bailey Ling.
+" vim: et ts=2 sts=2 sw=2
+
+function! airline#extensions#virtualenv#init(ext)
+  call a:ext.add_statusline_func('airline#extensions#virtualenv#apply')
+endfunction
+
+function! airline#extensions#virtualenv#apply(...)
+  if &filetype == "python"
+    let w:airline_section_x = '%{virtualenv#statusline()} '.g:airline_section_x
+  endif
+endfunction
+