Making parlour DSL immutable + adding getters to DSL

Making parlour DSL immutable + adding getters to DSL
Thank you for adding a test!
Can you please use the same style test as https://github.com/CommBank/parlour/blob/master/src/test/scala/au/com/cba/omnia/parlour/ExportSqoopRiffleSpec.scala. It is the test style we use across all our projects.