New layout, tests moved.
Change paths in docs and examples.
Final layout tweaks.

Remove test data from sdists. Check for it when running tests and
direct users to download location. No automated download... I don't
expect many users to be running the tests from an sdist.

Closes #133.
Oops, reduce moved to functools in Py3.
Merge pull request #134 from mapbox/new-test-layout

New test layout