ping: Tests for Ping and PingServer

This commit includes minor refactoring in Ping and PingServer to support unit testing

refs #2796

Change-Id: Id0172486aa07e129a90091d72594fbccbb5dbc06
diff --git a/tools/ping/server/ping-server.cpp b/tools/ping/server/ping-server.cpp
index f919113..799fa8d 100644
--- a/tools/ping/server/ping-server.cpp
+++ b/tools/ping/server/ping-server.cpp
@@ -40,14 +40,20 @@
 void
 PingServer::run()
 {
+  start();
+
+  m_face.getIoService().run();
+}
+
+void
+PingServer::start()
+{
   m_name.append("ping");
   m_face.setInterestFilter(m_name,
                            bind(&PingServer::onInterest,
                                 this, _2),
                            bind(&PingServer::onRegisterFailed,
                                 this, _2));
-
-  m_face.processEvents();
 }
 
 int
diff --git a/tools/ping/server/ping-server.hpp b/tools/ping/server/ping-server.hpp
index c5e9634..242a54a 100644
--- a/tools/ping/server/ping-server.hpp
+++ b/tools/ping/server/ping-server.hpp
@@ -65,6 +65,12 @@
   run();
 
   /**
+   * @brief starts the Interest filter
+   */
+  void
+  start();
+
+  /**
    * @brief gets the number of pings received
    */
   int