Some sidebar nav fixes.

- Set isExpanded state to false when window width is < 700px.
- Set `pointer-events` to `none` for logo to allow users to easily click on hamburger icon.

awx/ui/client/lib/components/layout/_index.less

@@ -49,6 +49,7 @@
                     width: @main-menu-width;
                     margin: @main-menu-margin;
                     flex: initial;
+                    pointer-events: none;
                 }
             }