Add missing _copy.pyx file.

Oops... good thing distutils had the good sense to put _copy.c in the
0.2 sdist. Closes #8. Thanks, @AsgerPetersen!
Add rasterio.five and remove six dependency.

Closes #9. Thanks, @mwtoews!
Add read-only crs_wkt attribute.

Closes #10.
Add bounds attribute and ul() method.

Closes #11.
Convenient gitignore