OGLE to local tests

This is just to show you what I changed; I'm going to make mine into an official PR onto master because it makes the tests work without any remote interaction.

The biggest changes were some cleanup in `core.py` that I think you had just left unfinished/untested and fixing the monkeypatching in the tests; you had `patch_get` being used, but the code only uses `post` (you only monkeypatch one of the `requests` methods, either `requests.get` or `requests.post`, not both, usually).