enable/disable features in config.json

As per https://docs.google.com/document/d/1Kn-mz2dDce9Cqc4oUTl5yJXGvmTlky1_KezuwUg58x0/edit#

Replaces:
 * enableLabs setting
 * 'override' flag in labs
 * 'default' flag in labs

Un-feature-flags matrix apps since this was now overidden to be
enabled.

src/components/structures/LoggedInView.js

@@ -1,6 +1,7 @@
 /*
 Copyright 2015, 2016 OpenMarket Ltd
 Copyright 2017 Vector Creations Ltd
+Copyright 2017 New Vector Ltd
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -250,7 +251,6 @@ export default React.createClass({
                 page_element = <UserSettings
                     onClose={this.props.onUserSettingsClose}
                     brand={this.props.config.brand}
-                    enableLabs={this.props.config.enableLabs}
                     referralBaseUrl={this.props.config.referralBaseUrl}
                     teamToken={this.props.teamToken}
                 />;