Implement auto-deploy to package manager

[Elmer Thomas]

Issue Summary

When all tests on the master branch pass in Travis CI, we would like to auto-deploy the release to the package manager.

Before writing any code, we suggest you review our CONTRIBUTING.md file and propose your solution for discussion here in the comments. Thank you!

Aceptance Criteria

• when Travis CI passes all tests on the master branch we auto-deploy to the package manager
• the version is determined by the CHANGELOG.md

[Eric Ho]

Hi, I would like to pick up this project.
Since the version is determined by CHANGELOG.md, how about we do the auto-deploy when a tag is pushed or a release is created in GitHub?

[Jake Plimack]

@dhoeric the version is defined in the gemspec https://github.com/sendgrid/ruby-http-client/blob/master/ruby_http_client.gemspec#L7

[Aboobacker MK]

https://docs.travis-ci.com/user/deployment/rubygems/ Here is the guide @dhoeric

[Elmer Thomas]

Thanks for taking this on @dhoeric!

Thanks for the guidance @kplimack & @tachyons!

[childish-sambino]

Fixed by #112