Fix so it run as it should.

- [x] Removed dup sub locale en-AU (exactly same as `en.yml`).
- [x] Removed i18n-spec (not needed with only 6 locale keys).
- [x] Removed old configuration spec.
- [x] Fix dependencies ([simplecov](https://github.com/colszowka/simplecov#important-notice-there-is-currently-a-bug-that-affects-exit-code-handling-on-the-08-line-of-simplecov-see-281-please-use-gem-simplecov--071-until-this-is-resolved) need to be locked at the moment).
- [x] Fix spec matcher (dunno why but it still use old TinyMCE version).
- [x] Add [Code Climate badge](https://codeclimate.com/github/spree/spree_editor) :)

@jdutil I manage to run it all smooth now.