Hide e2e features if not enabled

Don't show the device info in the MemberInfo and UserSettings unless the user
has ticked the 'labs' box.

src/components/structures/UserSettings.js

@@ -258,6 +258,10 @@ module.exports = React.createClass({
     },
 
     _renderDeviceInfo: function() {
+        if (!UserSettingsStore.isFeatureEnabled("e2e_encryption")) {
+            return null;
+        }
+
         var client = MatrixClientPeg.get();
         var deviceId = client.deviceId;
         var olmKey = client.getDeviceEd25519Key() || "<not supported>";