GUI -- Added UiViewHidden subclass of UiView to allow for views that do not have an entry in the navigation panel.
- Added placeholder "flow" view.

Change-Id: I3a969d16baf608b132c10cfc7f154d0ce51c765e
diff --git a/web/gui/src/main/webapp/index.html b/web/gui/src/main/webapp/index.html
index d90bdc8..a112c34 100644
--- a/web/gui/src/main/webapp/index.html
+++ b/web/gui/src/main/webapp/index.html
@@ -110,6 +110,7 @@
     <script src="app/view/topo/topoTraffic.js"></script>
     <script src="app/view/topo/topoToolbar.js"></script>
     <script src="app/view/device/device.js"></script>
+    <script src="app/view/flow/flow.js"></script>
     <script src="app/view/link/link.js"></script>
     <script src="app/view/host/host.js"></script>
     <script src="app/view/intent/intent.js"></script>
@@ -123,6 +124,7 @@
     <!-- Builtin views stylesheets. -->
     <link rel="stylesheet" href="app/view/topo/topo.css">
     <link rel="stylesheet" href="app/view/device/device.css">
+    <link rel="stylesheet" href="app/view/flow/flow.css">
     <link rel="stylesheet" href="app/view/link/link.css">
     <link rel="stylesheet" href="app/view/host/host.css">
     <link rel="stylesheet" href="app/view/intent/intent.css">