Style end session messages

Also add a missing call to render()

js/views/message_view.js

@@ -45,7 +45,7 @@
               model: groupUpdate
           }).render();
       } else if (this.model.get('flags') === textsecure.protobuf.PushMessageContent.Flags.END_SESSION) {
-          this.end_session_view = new Whisper.EndSessionView();
+          this.end_session_view = new Whisper.EndSessionView().render();
       } else {
         this.template = $('#message').html();
       }

stylesheets/_conversation.scss

@@ -216,3 +216,9 @@ button {
       z-index: 5;
   }
 }
+
+.end-session {
+  font: small;
+  font-style: italic;
+  opacity: 0.8;
+}

stylesheets/manifest.css

@@ -398,3 +398,8 @@ button {
     border: 0;
     outline: 0;
     z-index: 5; }
+
+.end-session {
+  font: small;
+  font-style: italic;
+  opacity: 0.8; }