Back on track, for now.

* Added "View Landing Page" feature spec to keep view specs honest;
* Created new, non-AR Blog model and spec;
* Reworked DescribeBlog interactor and spec to pass blog model as parameter;
* Updated controller code and spec to match new DescribeBlog parameter sequence;
* Added 'haml-rails' Gem (and reopened Issue #3) to work around serious WTF with my understanding of Slim + Rails;
* Fixed minor typo in Gemfile comment.

RSpec: 44 examples, 0 failures
Script: 0 tests: 0 failures, 0 errors, 0 pending, 0 omitted
RuboCop: 16 files inspected, no offenses detected
RuboCop global overrides in `.rubocop.yml`: 2