Fix various tests

See https://issues.apache.org/jira/browse/BROOKLYN-83 for more discussion.
I'm not sure how we bend resteasy to our will for that, especially given https://docs.oracle.com/cd/E19776-01/820-4867/ghrpv/ saying that it is the first method.
If there is no "Accepts" passed in, then how would we ensure that only one of the methods matches?

Anyway, not addressing in this PR.