Handle redacted events

matrix-js-sdk now retains redacted events. Filter them out of the timeline.

Also put empty placeholders in the dom so that if we try to scroll to a
redacted event, we don't end up blowing up.

src/components/views/rooms/EventTile.js

@@ -65,6 +65,7 @@ module.exports = React.createClass({
 
     statics: {
         haveTileForEvent: function(e) {
+            if (e.isRedacted()) return false;
             if (eventTileTypes[e.getType()] == undefined) return false;
             if (eventTileTypes[e.getType()] == 'messages.TextualEvent') {
                 return TextForEvent.textForEvent(e) !== '';