Made test suite more robust in failure; cleanup

Updated the chimpy test suite to not leave a mess behind if errors are
observed during the test run. Previously, innocuous errors like network
timeouts could leave the unittest in a state that would trip up
subsequent test runs (e.g. by leaving around merge vars, groups,
subscribers, etc). This commit means all failures in test cases are
captured and reported after the rest of the case has been allowed to
run.