show note and “powered by” when no acquire/sources plugins are used too

fixes #997

packages/@uppy/dashboard/src/components/AddFiles.js

@@ -35,6 +35,8 @@ class AddFiles extends Component {
               maxNumberOfFiles={this.props.maxNumberOfFiles}
             />
           </div>
+          { this.props.note && <div class="uppy-Dashboard-note">{this.props.note}</div> }
+          { this.props.proudlyDisplayPoweredByUppy && poweredByUppy(this.props) }
         </div>
       )
     }