Implement TextualEvent tiles for im.vector.modular.widgets

E.g. "Bob added a Acme widget", "Susan removed a Giraffe widget"

The name is calculated by taking the `name` in the event content, falling back on the `type`, falling back on the previous content `type`. This is then capitalised.

src/components/views/rooms/EventTile.js

@@ -44,6 +44,8 @@ var eventTileTypes = {
     'm.room.history_visibility' : 'messages.TextualEvent',
     'm.room.encryption' : 'messages.TextualEvent',
     'm.room.power_levels' : 'messages.TextualEvent',
+
+    'im.vector.modular.widgets': 'messages.TextualEvent',
 };
 
 var MAX_READ_AVATARS = 5;