Add event to kernel execution/shell reply.

This should allow to hook more easily phantomjs for testing.

IPython/frontend/html/notebook/static/js/kernel.js

@@ -245,7 +245,8 b' var IPython = (function (IPython) {'
             user_expressions : {},
             allow_stdin : false
         };
-		$.extend(true, content, options)
+        $.extend(true, content, options)
+        $([IPython.events]).trigger({type: 'Kernel.execution_request', kernel: this, content:content});
         var msg = this._get_msg("execute_request", content);
         this.shell_channel.send(JSON.stringify(msg));
         this.set_callbacks_for_msg(msg.header.msg_id, callbacks);
@@ -312,6 +313,7 b' var IPython = (function (IPython) {'
 
     Kernel.prototype._handle_shell_reply = function (e) {
         reply = $.parseJSON(e.data);
+        $([IPython.events]).trigger({type: 'Kernel.shell_reply', kernel: this, reply:reply});
         var header = reply.header;
         var content = reply.content;
         var metadata = reply.metadata;