CLN: Clean up imports.  Use absolute imports.
CLN: Lazy imports of matplotlib and descartes
TST: Remove matplotlib and descartes from requirements.txt (at least until there are plotting tests)
TST: Run Travis CI tests on 2.6 as well
Revert "TST: Run Travis CI tests on 2.6 as well"

This reverts commit dbbc9faefca88d739522e298e493d70f3ea5b406.
Merge pull request #31 from kjordahl/cleanup/imports

Clean up imports