add synth_id to response from synth-dependent services

[arlin]

Clients or users who employ subtree and induced_subtree may wish to have the synth tree version. This would be useful for the phylotastic project.

Add synth_id to response from subtree, induced_subtree, and any other services that return results dependent on the synth tree.

[josephwb]

This was implemented but was voted down. Fortunately most things were just commented out, so easy to do.

[josephwb]

E.g. this.

[jar398]

Clients who use the taxonomy may want to know the taxonomy version. Clients who use a study or collection may want to know the study or collection version. The latter is implemented in an idiosyncratic way in the phylesystem-api. I'm not sure what the otindex support for versioning is. It would be better if versioning wasn't added in a different way for each data type. There ought to be some common architecture, so that there is less to learn.

[josephwb]

I gather that there will be a drawn-out discussion on the best way forward by people who understand the best practices. For me, how versions are assigned is something that needs thought, and I would argue for consistency (but that isn't always seen as necessary). But reporting existing version numbers in query responses seems very straightforward. This is extremely relevant information (as is the taxonomy version), and I cannot fathom why would ever not provide it. We could satisfy @arlin's request immediately by reversing these commits:

4586db3
4c69297
0a33ce1
177c157

Please note: I only put this here for easy reference for the issue at hand. I know I didn't understand the issues last time around, and am not looking to be told how wrong I am. Whatever solution is best is best.