Use StatefulConnection class to verify connectivity in SG tests

There are two security group tests that are running for more than
20 minutes with RHEL image:
 - test_multiple_ports_portrange_remote
 - test_overlapping_sec_grp_rules
It happens because of the lack of privileges. I think it makes
sense to utilize the existing StatefulConnection class as it
has better service handling (start/stop) with all necessary
permissions

Change-Id: Iaca6fd3e6ed3c64ab3ca22817ad461479ecfa189
diff --git a/neutron_tempest_plugin/common/utils.py b/neutron_tempest_plugin/common/utils.py
index c28ce74..ab99db9 100644
--- a/neutron_tempest_plugin/common/utils.py
+++ b/neutron_tempest_plugin/common/utils.py
@@ -27,6 +27,7 @@
 
 import eventlet
 
+from oslo_log import log
 from tempest.lib import exceptions
 
 from neutron_tempest_plugin import config
@@ -37,6 +38,7 @@
     "https": 443,
 }
 CONF = config.CONF
+LOG = log.getLogger(__name__)
 
 
 class classproperty(object):
@@ -202,20 +204,30 @@
                         timeout=self.test_timeout,
                         sleep=self.test_sleep)
         try:
+            LOG.info("Checking connectivity between server and client -"
+                    " attempt {}".format(self.test_attempt))
             self.server_ssh.exec_command(
                     'grep {} output.txt'.format(self.test_str))
             self.client_ssh.exec_command(
                     'grep {} output.txt'.format(self.test_str))
             if not self.should_pass:
+                LOG.warning("attempt {} succeed while it should fail".format(
+                    self.test_attempt))
                 return False
             else:
                 if not self.connection_started:
                     self.connection_started = True
+                LOG.info("attempt {} succeed as it expected".format(
+                    self.test_attempt))
                 return True
         except exceptions.SSHExecCommandFailed:
             if self.should_pass:
+                LOG.warning("attempt {} failed while it should pass".format(
+                    self.test_attempt))
                 return False
             else:
+                LOG.info("attempt {} failed as it expected".format(
+                    self.test_attempt))
                 return True
         finally:
             self.test_attempt += 1