Introduce recent to Follow, as Account and other models have.
This change also adds specs for the scope and the dependents.

* add annotate to Gemfile

* rails g annotate:install

* configure annotate_models

* add schema info to models

* fix rubocop to add frozen_string_literal

StreamEntry model. Simply render Salmon slaps as they are needed

and atom feed generation to some extent, as well as the way mentions are
stored