API Explorer: Minor usability improvements

[colemanw]

Auto-open selectors, add more to the "options" list, and remove redundant clear "x" buttons and allow sorting of return value.

[eileenmcnaughton]

@colemanw I would have merged this but I think now Andrew is doing release notes we need to get tighter on logging JIRA for trivial things like this.

[colemanw]

As I recall @agh1 requested that we do a PR for each change and not merge commits directly to master (as I do sometimes in my lazier moments). I don't recall him saying there also has to be a jira ticket.

[agh1]

@colemanw @eileenmcnaughton no ticket is fine (at least for the near future pending a new approach to the release notes); it's the direct commits that are the problem. Of course, if there is a substantive change worth explaining/tracking, a ticket is nice, but I don't need it for the notes.