Make javelin2's ping for longer

Since as far as I can tell ping doesn't have a good way to ping until it
gets a response or until x seconds pass, use a python loop to do it
instead.

Change-Id: If05c373f30f515af82fecf2347d7f7c1a5824287
diff --git a/tempest/cmd/javelin.py b/tempest/cmd/javelin.py
index ca79cf1..f2127bb 100755
--- a/tempest/cmd/javelin.py
+++ b/tempest/cmd/javelin.py
@@ -244,9 +244,13 @@
             r, found = client.servers.get_server(found['id'])
             # get the ipv4 address
             addr = found['addresses']['private'][0]['addr']
-            self.assertEqual(os.system("ping -c 1 " + addr), 0,
-                             "Server %s is not pingable at %s" % (
-                                 server['name'], addr))
+            for count in range(60):
+                return_code = os.system("ping -c1 " + addr)
+                if return_code is 0:
+                    break
+            self.assertNotEqual(count, 59,
+                               "Server %s is not pingable at %s" % (
+                               server['name'], addr))
 
     def check_volumes(self):
         """Check that the volumes are still there and attached."""