The Jumbotron font-size LESS variable now conforms to the...

The Jumbotron font-size LESS variable now conforms to the '@{bootstrapClass}-font-size' naming scheme.

less/jumbotron.less

@@ -6,7 +6,7 @@
 .jumbotron {
   padding: @jumbotron-padding;
   margin-bottom: @jumbotron-padding;
-  font-size: @font-size-jumbotron;
+  font-size: @jumbotron-font-size;
   font-weight: 200;
   line-height: (@line-height-base * 1.5);
   color: @jumbotron-color;