Placeholder blog posts are no longer being used.

Also:

* Fixed typo in application layout (but see latest note on Issue #9);
* Removed #reset action from BlogController (this branch never routed
  it from the app level);
* Changed feature spec from "User can view placeholder posts" to "User
  CANNOT view placeholder posts".

RSpec: 81 examples, 0 failures
Script: 0 tests: 0 failures, 0 errors, 0 pending, 0 omitted
RuboCop: 27 files inspected, no offenses detected
RuboCop global overrides in `.rubocop.yml`: 2
RuboCop local overrides in our source/spec files: 5