mark setup.py as no longer released
Add pypi badge to README
use pypi url directly
Add setup.cfg to facilitate building wheels
add _maybe_promote to core.common
fix silently upcasting float32 to float64 in reindex/align

Fixes #264
reorg _as_compatible_data
Convert masked arrays properly

Fixes #259.
Merge pull request #269 from shoyer/dtype-casting

Fixes for dtype casting
Fix guess_time_units if NaT is present
Merge pull request #270 from shoyer/fix-guess_time_units-NaT

Fix guess_time_units if NaT is present
Add backends integration test for roundtripping datetime arrays

Not sure how we missed this before.

Also includes a fix for writing datetime arrays with missing values.
Merge pull request #271 from shoyer/serialize-datetime

Add backends integration test for roundtripping datetime arrays
Fix docstring typo in align()
Merge pull request #275 from WeatherGod/doctypo

Fix docstring typo in align()
small refactor to canonicalize_indexer
Merge pull request #281 from shoyer/small-indexing-tweak

small refactor to canonicalize_indexer
Fix to_netcdf with 0d sting variables

Fixes #284
fix serialization on Python 3 (use a char array)
Serialize non-index coordinates to netCDF files

Fixes GH231

This PR ensures non-index coordinates can be roundtripped to netCDF and
back by using the CF convention of the 'coordinates' attribute on a "data
variable".

In cases where there are no data variables available, we fall back to the
(extended, non-CF) convention of saving 'coordinates' as a global attribute.

I also added the `xray.decode_cf` function to the API. This function can
decode either datasets or datastores into decoded datasets, which is handy,
for example, if a dataset is serialized according to CF conventions but already
in memory (e.g., saved in JSON).

akleeman: I could use some guidance from you on want to do about
`test_roundtrip_coordinates` on `TestCFEncodedDataStore`. I am tentatively
skipping it, but it would be nice to get it working. To do so will require
some tweaks to the API for the `Datastore.load` method.