Removed previous commit: "Updated RSpec dummy app as Rails 4.2.x dummy
app."

- This reverts commit f03caf33f2879aa251443a03c5151e55652ab0f1.
- Was too hasty in upgrading the dummy app to Rails 4.2.x support as
  it breaks Rails 4.1.x testing.
Removed `respond_to` support.

- Was unnecessary and is being removed in Rails 4.2.x.