Update Multiselect.jsx

fixes jquense#193

Author: jquense

src/Multiselect.jsx

@@ -215,7 +215,7 @@ var Multiselect = React.createClass({
           ref='status'
           id={instanceId(this, '__notify')}
           role="status"
-          className='sr-only'
+          className='rw-sr'
           aria-live='assertive'
           aria-atomic="true"
           aria-relevant="additions removals text"