Parametrize JSON tests
lot more to be done here but split these up as some of the large functions are difficult to highlight failures while working on extension module. Improved coverage and identified some inconsistencies in process (marked with TODOs) which can be tackled as follow ups
Hello @WillAyd! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:





There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers: 

##### Comment last updated at 2019-09-17 04:19:20 UTC @WillAyd can you rebase looks like PY35 is not defined? My bad - good find Finally green...the parametrization process revealed quite a few inconsistencies with our JSON parsing, namely:

 - read_json sorts when `orient="index"` and `numpy=False` (default value)
 - read_json sorts when Py35 and, `numpy=False` (default value) and `orient="columns"`
 - read_json returns `np.int32` on Windows and 32 bit platforms when `orient` is anything other than `split`
 - read_json with `orient="split"` does not preserve numeric column / index values, though it should be able to
 - read_json with `dtype=False` will read in `null` values as `None` instead of `np.nan`
 

The Py35 issues are probably moot at this point but happy to open up follow up issues for the rest if no other changes are required here nice, ill give this a read Anyone have thoughts on this one? I think should be good to go Looking commit-by-commit most of them look pretty straightforward, but the _check_all_orients refactor is pretty imposing.  Would doing this in smaller pieces be burdensome?

Are the tests substantively changed or just parametrizing existing tests?

Sorry for the delay in review. @WillAyd gonna make another pitch for splitting this into smaller pieces to keep forward momentum Sure no problem. Are you just looking for `test_frame_from_json_to_json` to be in a separate PR? > Are you just looking for test_frame_from_json_to_json to be in a separate PR?

I think that'd go a long way, yah. Sorry for delay but should be done now. I ultimately plan to just revert these last two commits in a subsequent PR but I think this should make review more manageable on this one. lmk what you think I think I've marked all the funcs with clear one-to-one changes.  Happy to merge those, the others I need more time and caffeine @WillAyd can you rebase and i'll make a big push to get this reviewed this afternoon Done and thanks! These parametrization ones aren't the most fun to review so much appreciated @WillAyd a handful of comments, generally LGTM.  This is going to be much nicer when you're done here, thanks for doing it. OK last 3 commits should address outstanding comments. Let me know what you think and thanks again for the review @WillAyd LGTM, thanks.

There are a couple of threads in the diff that are unresolved that would make for nice follow-ups, but nothing that is a blocker.  Merging.