Version 1.1: vespa compatibility; py3; fix dartmouth; better testing

This version will now be compatible with vespa, after vespa's next upgrade.

Also this release fixes a major issue with the dartmouth.tri file that was breaking with scipy 0.19. Everything should also now be python 3-compatible.

To use 1.1, you will have to delete the dartmouth tables in your .isochrones (or $ISOCHRONES) directory, and then let the code re-download them for you.

Documentation has still not been updated, but will be with the next release. This is a functional quick-fix for the major issues, and documentation will follow.