Synth browsing: we need to bounce back to the MRCA of the constituent taxa

[mtholder]

Currently if a higher taxon is monophyletic, we don't present a variable helpful UI. See:

https://tree.opentreeoflife.org/opentree/argus/ottol@34907/Drosophila-genus-in-Holozoa-

We now have (for each synth version) a file like: http://files.opentreeoflife.org/synthesis/opentree5.0/output/labelled_supertree/broken_taxa.json

Which provides among (other things) the MRCA for all of the tips that descend from a non-monophyletic taxon.

We need to:

1. design some simple API that takes an OTT ID are returns that MRCA, or an error to indicate that the OTT ID does not correspond to a "broken" taxon.
2. implement that somewhere. Presumably it just reads that JSON file and looks for the ottID in the non_monophyletic_taxa object.
3. implement some method to tell that web service when there is a new version of synth (and hence a new file to read).
4. implement the UI side that calls this service whenever the request to tm-lite for the higher level taxon fails.

[mtholder]

see also OpenTreeOfLife/opentree#836

[mtholder]

fixed at all hands meeting