Preapre for release

Fix travis config for osx

Bump version to 1.3.1

Prepare for 1.3.0 release

Add link to documentation

Add ruby 2.4 to travis ci

Add concrete version number for development dependency pry-byebug.

increase version numbers for 1.2.3 release

add another example

Update Releases.

Update version number to be able to re-push to rubygems.