Fix e2e attachment download by using iframes. (#562)

* Render attachments inside iframes.

* Fix up the image and video views

* Fix m.audio

* Comments, and only use the cross domain renderer if the attachment is encrypted

* Fix whitespace

* Don't decrypt file attachments immediately

* Use https://usercontent.riot.im/v1.html by default

* typos

* Put the config in the React context.

Use it in MFileBody to configure the cross origin renderer URL.

* Call it appConfig in the context

* Return the promises so they don't get dropped

src/components/structures/MatrixChat.js

@@ -66,10 +66,20 @@ module.exports = React.createClass({
         defaultDeviceDisplayName: React.PropTypes.string,
     },
 
+    childContextTypes: {
+        appConfig: React.PropTypes.object,
+    },
+
     AuxPanel: {
         RoomSettings: "room_settings",
     },
 
+    getChildContext: function() {
+        return {
+            appConfig: this.props.config,
+        }
+    },
+
     getInitialState: function() {
         var s = {
             loading: true,