#491 - Remove chef/mixin/language references to support Chef 14

[sherenator]

This addresses the same issue (issue #491 ) as pull request #494 , however the Travis CI build now passes.

• Removed chef/mixin/language references to support Chef 14
• Pinned versions for 'cucumber-core' as well as 'gherkin'
• Bumped Ubuntu version in spec tests to support current fauxhai version.