Quandl

* Removes pointless print statements from datatable model.

Drop support for Python 2 and Python < 3.5. See [here for more info](./DROP_PYTHON_EOL_SUPPORT.md).

* This version is the last `quandl` version to support Python 2 or < 3.5. All future `quandl` package releases will only support Python >= 3.5.

If you're still using Python 2 or < 3.5, you'll need to stay at this version.

If you're using Python >= 3.5, its recommended you perform a `pip install --upgrade quandl` to grab the newest
version.

* Add config to verify SSL certs. Verification on by default. (135)

* Fix typo in invalid database code message (128)
* Use six.moves instead of try/catch on imports (129)
* Add classifiers metadata to setup.py (132)
* Update how we find local api key file (131)

* Use POST requests for some datatable calls https://github.com/quandl/quandl-python/pull/126