Added retries for db_sync

If db sync fails, it is never retried leading to errors. So, this
patch adds retries for db_sync to avoid sync fails.

Change-Id: I6117fc818c44ac31ae656c18ed7fe5434fa73b77
Closes-Bug: #1628580

manifests/db/sync.pp

@@ -26,6 +26,8 @@ class ceilometer::db::sync(
     path        => '/usr/bin',
     user        => $::ceilometer::params::user,
     refreshonly => true,
+    try_sleep   => 5,
+    tries       => 10,
     logoutput   => on_failure,
   }