Use correct Ruby version in README

The gemspec specifies Ruby >= 2.0.0 so remove mention of 1.9
Merge pull request #278 from stevenwilkin/correct-ruby-version-in-readme

Use correct Ruby version in README
Update Changelog.md
Sync devtools
Remove evaled Gemfile components of devtools
Add emit of naked guard body

[fixes #280]
Fix silent exclusion of metadata duplicates in rspec integration
Prevent ignore of metadata duplicates in rspec integration

* Example groups with identical metadata still can represent different
  test cases.
* Using the relative example group index as an additional key resolves
  this.

[fixes #279]
Fix style
Update travis matrix and container config
Use latest 2.1 ruby on circle
Adjust reek config
[WIP] Implement line tracing for spec selection