Mongo runCommand is not being instrumented

[jorkzijlstra]

In relation to #994, I noticed that the runCommands are not being instrumented, not even in the older 2.8.0 driver.

I was expecting this command to show up in the metrics but it doesn't

    val isServerOk = Document("serverStatus" -> 1, "repl" -> 1)

    mongoDatabase
      .runCommand(isServerOk)