Centering select2 vertically

This makes Select2 behave much more sane when it's put inline inbetween
text.

select2.css

@@ -7,7 +7,7 @@ Version: @@ver@@ Timestamp: @@timestamp@@
     /* inline-block for ie7 */
     zoom: 1;
     *display: inline;
-    vertical-align: top;
+    vertical-align: middle;
 }
 
 .select2-container,