Added "Copy yaw" button to HDRIs

The button is only shown to people with the right to edit the current
node. I've also simplified some CSS, with the help of @venomgfx.

src/templates/vrview.jade

@@ -18,8 +18,6 @@ html(lang='en')
     script.
         /** Returns the current yaw in degrees. */
         function yaw() {
-            console.log('default yaw:', worldRenderer.sceneInfo.defaultYaw * 180 / Math.PI);
-            console.log('camera rotation: ', worldRenderer.camera.rotation.y * 180 / Math.PI);
             var the_yaw = worldRenderer.sceneInfo.defaultYaw + worldRenderer.camera.rotation.y;
             return the_yaw * 180 / Math.PI;
         }