Upgrade to Synnefo v0.16.2

Since Synnefo v0.16.2 is mostly a bug fix version, the downtime required for the upgrade should be minimal. Following the usual process, bring the services down and upgrade the packages. Before bringing the services back up, you should run snf-manage migrate on the astakos node, in order to fix the quotas of users enrolled but not accepted in projects, which might be out-of-sync.