Packs are now loaded from views, just like upstream, and are
identified by their filenames. The definition of `theme.yml` has
changed as such:
- `pack_directory` is now required
- `pack` is now unused
- `signed_in_preload` has been introduced
* Run rubocop --autocorrect on app/, config/ and lib/, also manually fix some remaining style issues
* Run rubocop --autocorrect-all on db/
* Run rubocop --autocorrect-all on `spec/` and fix remaining issues
Claire