Attempt to further address Issue #9.

Se've got the "success" green background showing now, but the click-the-
`times`-symbol-to-dismiss-the-flash-message behaviour does NOT work,
despite slavishly copying the example markup in the Bootstrap docs at
http://getbootstrap.com/components/#alerts-dismissable for Bootstrap 3.

RSpec: 1032 examples, 0 failures
Script: 0 tests: 0 failures, 0 errors, 0 pending, 0 omitted
RuboCop: 35 files inspected, no offenses detected
RuboCop global overrides in `.rubocop.yml`: 2
RuboCop local overrides in our source/spec files: 5