Finalize configuration schema

[dluc]

Current schema:

• Multiple blocks
• camelCase

iothub {
    ...auth settings...
}

iothub-stream {
    ...streaming settings...
}

iothub-checkpointing {
    ...checkpointing settings...
}

Proposed schema

• One block
• dashes, no camelCase (like akka http://doc.akka.io/docs/akka/current/general/configuration.html)

iothub-react {
    auth {
        ...auth settings...
    }

    streaming {
        ...streaming settings...
    }

    checkpointing {
        ...checkpointing settings...
    }
}