[Review] Request from 'aduffeck' @ 'SUSE/machinery/review_140917_remove_global_puts_stub'

Please review the following changes:
  * ebfa1de Encapsulate all machinery output into Machinery::Ui methods
I'm fine with doing this as a first step of fixing #165, but it doesn't completely solve the issue. We should not generally stub all output, but only where it is actually needed to do specific tests. Otherwise we don't capture output at places where it's not supposed to be.