Make the config optional

Accept 404 errors from getting the config and start MatrixChat with no config, make other errors display a simple error message to prevent a completely blank page if the config does fail to load.

src/components/views/settings/Notifications.js

@@ -121,6 +121,8 @@ module.exports = React.createClass({
             var data = {}
             if (this.props.brand) {
                 data['brand'] = this.props.brand;
+            } else if (this.props.brand === undefined) {
+                data['brand'] = 'Vector';
             }
             emailPusherPromise = UserSettingsStore.addEmailPusher(address, data);
         } else {