[Buildbot] #3457: Test all supported versions of MySQL, postgres in metabuildbot

[Buildbot trac]

#3457: Test all supported versions of MySQL, postgres in metabuildbot
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Reporter:  dustin  |      Owner:  dustin
    Type:  task    |     Status:  new
Priority:  minor   |  Milestone:  ongoing
 Version:  0.8.12  |   Keywords:
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 We have db-mysql and db-postgres, but they are just testing whatever
 version is on hand on that worker.

 We should, instead, test the whole range of DB versions we support, the
 latest version of each.  I think that means

  * mysql-5.4
  * mysql-5.5
  * mysql-5.6
  * mysql-5.7
  * postgres-9.3
  * postgres-9.4
  * postgres-9.5

 I have an email out to the users list to see what versions of MySQL people
 expect to see supported.

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Ticket URL: <http://trac.buildbot.net/ticket/3457>
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Buildbot: build/test automation