Normalization of dates in responses from query command

[johnerikhalse]

The command veidemannctl report query allows to write raw RethinkDb queries to Veidemanns config database.
When such a query returns a structure containing a date element, it is formatted as it is represented in RethinkDb like this:

{
  "dateTime":{
    "date":{
      "year":2019,
      "month":2,
      "day":21
    },
    "time":{
      "hour":13,
      "minute":29,
      "second":55,
      "nano":324000000
    }
  },
  "offset":{
    "totalSeconds":0
  }
}

When the database is accessed with the regular get/set update commands, the format defined by RFC3339 is used. This PR detects RethinkDb dates in query responses and converts them to RFC3339 format.

[trym-b]

The PR description looks good to me, perhaps add it to the commit message for increased discoverability?

Since this PR fixes a regression if I recall correctly, is it possible to add a test so we avoid ending up in the same state later?

[trym-b]

Perhaps rename to query-template.yaml