Remove RSpec config.

If a default RSpec config is required, setting `~/.rspec` is better than
setting it per repository.
Flatten factories into a single file.

This makes the factories, which will likely each only be a few lines,
more easily maintainable.
Change custom RSpec accessible|protected matchers to use submodule.

These RSpec matchers are not really specific to the repository, and have
been moved to a GitHub Gist. Change the matchers to use a Git submodule,
which should work even if the Gist is deleted.

To set up all submodules for a repository:

    git submodule update --init --recursive
Merge branch 'refactor/test' into develop