Merge pull request #3 from N-Manos/dev

Dev
Merge pull request #4 from N-Manos/dev

Add user authentication system with devise and associated tests.
Adding author and editor roles with tests for creating and publishing posts with each.
Add gems and ensure all tests passing before adding Pundit.
Added background image to site and styled top nav bar.

Minor editing a post test fix due to restyling of site.