Update worthwhile and associated gems

Note: I had to `gem update bundler` to get around 
some compatibility issues involving sprockets.

bundle update worthwhile
Worthwhile no longer depends on hydra gem
Run the worthwhile generator

This is the result of running `rails generate worthwhile:install`.

We had to make a couple tweaks to get it to complete successfully:
- Temporarily remove the root route
- Put an application.js back in place
- Create an empty Ability model

For better or for worse, this is almost the exact resulting output.