Convert People screen to use Views (like the Content screen)

Would admin views be an idea instead for both

admin_views ships its own Content view, which would conflict with commerce_backoffice. That's why we didn't add it in the first place.
Perhaps we could add it, and then disable its content view.

I could see this being viable, especially since most sites use it. If we're also implementing a fix to disable the admin_views content override, then we'll mitigate that bug for other users, too, who might experience it if we don't add admin_views.

Thoughts, bojanz?

Turns out Commerce Backoffice does disable admin_views conflicts!

/**
 * Implements hook_views_default_views_alter().
 *
 * Disable the content view provided by the admin_views module.
 */
function commerce_backoffice_content_views_default_views_alter(&$views) {
  if (isset($views['admin_views_node'])) {
    $views['admin_views_node']->disabled = TRUE;
  }
  if (isset($views['admin_views_comment'])) {
    $views['admin_views_comment']->disabled = TRUE;
  }
}

Build: https://travis-ci.org/commerceguys/commerce_kickstart/builds/71805324 (with tests checking its working)