Support logging VM credentials

- In JcloudsLocation, if config says so then log the password/privateKey
- Useful for when debugging failing to ssh (e.g. in vcloud-director!), 
  but config should never be used in production!
RebindOptions (in tests): make public

- Let RebindOptions be used in downstream projects
Adds YamlLauncher.launchAppYaml(Reader) for tests
Add tests for Postgres restart/rebind

- And changes Postgres connectSensors() to use
  connectServiceUpIsRunning(), given that was all
  the feed was doing anyway.
Add MongoDBRestartIntegrationTest
restart/rebind tests: incorporate review comments
This closes #402