Update navigation bar to more gracefully handle extreme scenarios

 - Sometimes the middle nav is dynamic (including titles), which means it could be inordinately large.  For now, we'll handle this by setting a max size on the middle nav and setting overflow in the horizontal direction.  In the future, the menu-bars that get placed in the middle nav should take this into account and gracefully degrade.

catalog/ui/catalog-ui-search/src/main/webapp/component/navigation/navigation.less

@@ -5,6 +5,7 @@
   color: @text-color;
   height: 60px;
   overflow: hidden;
+  white-space: nowrap;
   .vertical-borders(1px, @heavily-lighten-inherited-background-color);
 
   > .navigation-left,
@@ -51,4 +52,11 @@
     text-align: center;
   }
 
+  > .navigation-middle {
+    max-width: ~'calc(100% - 450px)';
+    overflow-x: auto;
+    overflow-y: hidden;
+    text-overflow: ellipsis;
+  }
+
 }