Python-sa-gwdata

What's Changed
* Changes to docs by kinverarity1 in https://github.com/kinverarity1/python-sa-gwdata/pull/27
* Fix for 28 - handle np.nan arg values for UnitNo and ObsNo constructors by kinverarity1 in https://github.com/kinverarity1/python-sa-gwdata/pull/29
* Retry on ConnectionError by kinverarity1 in https://github.com/kinverarity1/python-sa-gwdata/pull/30
* Accommodate setting unit number via unit_hyphen or unit_long by kinverarity1 in https://github.com/kinverarity1/python-sa-gwdata/pull/32
* Local data cache, starting with drillhole layer from the spatial data downloads page (WIP) by kinverarity1 in https://github.com/kinverarity1/python-sa-gwdata/pull/31
* Fix docs by kinverarity1 in https://github.com/kinverarity1/python-sa-gwdata/pull/34
* Fix __version__ issue by kinverarity1 in https://github.com/kinverarity1/python-sa-gwdata/pull/36
* Breaking changes to ObsNo and UnitNo by kinverarity1 in https://github.com/kinverarity1/python-sa-gwdata/pull/37


**Full Changelog**: https://github.com/kinverarity1/python-sa-gwdata/compare/v0.11...v0.12

What's Changed
* Ignore aquifers with no code (fix 23) by kinverarity1 in https://github.com/kinverarity1/python-sa-gwdata/pull/25
* Fix 24 by kinverarity1 in https://github.com/kinverarity1/python-sa-gwdata/pull/26


**Full Changelog**: https://github.com/kinverarity1/python-sa-gwdata/compare/v0.10.2...v0.11

Add all bulk data download methods (see documentation)

- Add ``find_wells``, ``water_levels``, ``salinities`` and ``drillers_logs`` functions
- Complete documentation of JSON webservices

- Add ``find_wells_in_lat_lon()`` method
- Fix ``"nan"`` bug for ``UnitNo``
- Fix correct ``pandas`` dependency requirement