use rest-client 2.0 to fix issue with OpenSSL 1.1.0

[ushis]

Pull Request Checklist

Fixes #81

General

• [x] Update Changelog following the conventions laid out on Keep A Changelog

• [ ] Update README with any necessary configuration snippets

• [ ] Binstubs are created if needed

• [ ] RuboCop passes

• [ ] Existing tests pass

New Plugins

• [ ] Tests

• [ ] Add the plugin to the README

• [ ] Does it have a complete header as outlined here

Purpose

fix

Known Compatibility Issues

none

[majormoses]

@ushis looks like that introduces a breaking change that forces us to drop ruby 2.1 which is still a supported version of ruby so we need to figure out of we can lock this dependency: https://travis-ci.org/sensu-plugins/sensu-plugins-http/jobs/258855032#L561 to keep ruby 2.1 support for this to be accepted. Our official stance is regarding ruby version support: https://github.com/sensu-plugins/documentation/blob/master/docs/FAQ.md#what-is-the-policy-on-supporting-end-of-lifeeol-ruby-versions.

[ushi-as]

@majormoses According to the travis log, this is a problem introduced by kitchen-localhost, not by rest-client.

Gem::InstallError: mixlib-shellout requires Ruby version >= 2.2.
An error occurred while installing mixlib-shellout (2.3.2), and
Bundler cannot continue.
Make sure that `gem install mixlib-shellout -v '2.3.2'` succeeds before
bundling.

In Gemfile:
  kitchen-localhost was resolved to 0.3.0, which depends on
    test-kitchen was resolved to 1.16.0, which depends on
      mixlib-install was resolved to 2.1.12, which depends on
        mixlib-shellout

[majormoses]

@ushi-as ok, can you lock down that down to make it work with ruby 2.1?

[ushis]

@majormoses done

[majormoses]

released: https://rubygems.org/gems/sensu-plugins-http/versions/2.6.0