Fix streaming output arg

Note that while there are no explicit tests in this PR for the
streaming output arg fix, there are in fact actually tests for this (both
unit and integration).

The problem was that we weren't checking the RC of the command that
was run, only that the request params looked how we wanted them to.

As a result, I've updated the
base test class to check for expected RCs from the commands that are
run.  This caused the tests to fail and should ensure that if we
break the streaming output arg customization, we'll get a test failure.

I've also included a fix for an integration test.  With this PR merged,
the integrations tests should finally be passing again (yay).