Wire up jump-to-bottom knob

... which I embarassingly forgot

src/components/structures/RoomView.js

@@ -1568,9 +1568,10 @@ module.exports = React.createClass({
                 tabCompleteEntries={tabEntries}
                 numUnreadMessages={this.state.numUnreadMessages}
                 hasUnsentMessages={this.state.hasUnsentMessages}
-                onResendAllClick={this.onResendAllClick}
                 atEndOfLiveTimeline={this.state.atEndOfLiveTimeline}
                 hasActiveCall={inCall}
+                onResendAllClick={this.onResendAllClick}
+                onScrollToBottomClick={this.jumpToLiveTimeline}
                 />
         }