Use new Hyrax devise styles

[no-reply]

This takes advantage of the new login form styles in samvera/hyrax#3362.

[bess]

@no-reply CI is failing :(

  1) Create a GenericWork a logged in user 
     Failure/Error: Unable to find matching line in /home/travis/build/curationexperts/nurax/app/assets/stylesheets/hyrax.scss
     
     Sass::SyntaxError:
       File to import not found or unreadable: hyrax/login_signup.

[no-reply]

@bess it looks like CI is running an older version of Hyrax than the actual builds. https://travis-ci.org/curationexperts/nurax/builds/454710578#L1199

This is probably because Gemfile.lock is checked in. We could add a bundle update hyrax to the build, or simply drop Gemfile.lock. I'm guessing the bundle option is more like what's happening on the nightlies?