CBQE-0 : observe tests don't run teardown if setup failed

Change-Id: I8b3d0df682989f9074c69efb43f0a221266730a4
Reviewed-on: http://review.couchbase.org/38065
Tested-by: Meenakshi Goel <meenakshi.goel@globallogic.com>
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Reviewed-by: Meenakshi Goel <meenakshi.goel@globallogic.com>