Test failure: 'Staging...' missing from output

Go cli commit e41c9e5376773132580a363ed127a0faa51da15d removed the
'Staging...' message but the test still expects it.  This removes that
expectation.
Merge pull request #2 from sykesm/staging-failure

'An application being staged has its staging log streamed during a push' fails with newer go cli