Log Message:
Update ruby-term-ansicolor to 1.6.0.

Quote from commit log

v1.4.1

* Always return a string from yield
* Be more accurate for triple html colors
* Test on ruby 2.4.1
* Remove codeclimate stuff

v1.6.0

* Implement HSL colors and a couple of cool methods
* Use license Apache 2.0 starting from version 1.6.0