update changelog, increase version for release 0.18.5

Merge pull request adafruit#434 from adafruit/develop

clean up for release 0.18.0

release 0.17.0

Increase version to 0.16.0 for release

update changelog

increase version to 0.15.1 for release

disable travis build

increase version & add changelog for release

increase version for release, update changelog

update readme

update release date

increase verion to 0.13.0, ready to release