Add TeVCat

TeVCat ( http://tevcat.uchicago.edu/ ) is an online catalog of TeV gamma-ray sources that is continuously updated and I would like to add it to astroquery.

I already have code to make astropy tables from their JSON data.
At the moment I do `View -> Developer -> JavaScript Console` in the Chrome browser and type `jsonData`.
The one thing I don't know how to do is how to get the data from Python.
@keflavich Do you know how to do that? Wout `TeVCat` be acceptable for `astroquery` or do you think it's too niche?


Did you really mean `astroquery.query.Astroquery`? (it isn't listed in `__all__` and doesn't have a docstring, so it doesn't appear in the docs)

I see that some other services subclass `astroquery.query.BaseQuery` and add an `async_to_sync` decorator ... is that what I'm supposed to do here?

For now I'll switch to simply use the `requests` module here ... maybe this is OK in this case because this class is an implementation detail and not part of the public API?