Refactor delayed verdict handling and add configurable retries (#52)

Extract HandleDelayedVerdict() to eliminate duplication and make
retry count and polling time configurable. Add delayed verdict
handling to SendRequestEnd with unit tests.

attachments/nano_attachment/nano_attachment_util/nano_attachment_util.cc

@@ -155,6 +155,18 @@ getWaitingForVerdictThreadTimeout()
     return conf_data.getNumericalValue("waiting_for_verdict_thread_timeout_msec");
 }
 
+unsigned int
+getHoldVerdictRetries()
+{
+    return conf_data.getNumericalValue("hold_verdict_retries");
+}
+
+unsigned int
+getHoldVerdictPollingTime()
+{
+    return conf_data.getNumericalValue("hold_verdict_polling_time");
+}
+
 int
 isIPAddress(c_str ip_str)
 {