Reset keepalive timer if we're about to send

No sense in sending more keepalives than necessary.

js/libtextsecure.js

@@ -15950,6 +15950,7 @@ window.axolotl.sessions = {
         };
 
         function send(msg) {
+            resetKeepAliveTimer();
             socket.send(msg);
         };
 

libtextsecure/websocket.js

@@ -70,6 +70,7 @@
         };
 
         function send(msg) {
+            resetKeepAliveTimer();
             socket.send(msg);
         };