Descarteslabs

* Adds doctests
* Fix py3 login compatibility

This enables searching by some of the fractional values in the metadata: cloud_fraction, cloud_fraction_0, and fill_fraction.

Fixes install process, updates Metadata interface.

This release renames arguments like shapes, geom, and location to be consistent throughout the api.

place: A named place identified by a slug
cutline: A shape used in raster/ndarray to crop an image to a cutline
geom: A GeoJSON geometry used primarily in metadata.search

Fix dependencies in pypi setup.