ENH: Use new pandas __finalize__ method
ENH: Use new __finalize__ method in GeoDataFrame too
TST: re-enable skipped tests
ENH: Define new _constructor property for GeoPandas objects
     Special fillna method is no longer needed for recent pandas versions.
     Need an extra check in __getitem__ to return a DataFrame if no geometry
TST: fillna needs argument now, and takes method argument
TST: Enable groupby test
BUG: Fix breakage on pandas <= 0.12
TST: Skip groupby test in pandas 0.12; add fillna test asserts
CLN: Use absolute imports in __init__ + add to namespace for interactive work
ENH: Send GeoDataFrame contents to geojson.io

Adds a to_geojsonio() method to GeoDataFrame which will open a web browser
and display the data to http://geojson.io. If the data is too large to be
included in the URL, a Github gist will be created and geojson.io will use the
data from the gist.