add license for responsive and rebuild

docs/assets/css/bootstrap-responsive.css

@@ -1,3 +1,12 @@
+/*!
+ * Bootstrap Responsive v2.0.0
+ *
+ * Copyright 2012 Twitter, Inc
+ * Licensed under the Apache License v2.0
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Designed and built with all the love in the world @twitter by @mdo and @fat.
+ */
 .hidden {
   display: none;
   visibility: hidden;