Cannot use markdown documents in theme directory

[preaction]

When adding a markdown file to a theme directory, perhaps to add a README file, or some random markdown-based include, we get an error during the deploy process:

Can't call method "theme" on an undefined value at /home/bill/perl5/perlbrew/perls/perl-5.22.0/lib/site_perl/5.22.0/Statocles/App/Role/Store.pm line 44.

This is likely because the Statocles::Theme class overrides the template method, and also perhaps because the theme object doesn't get a site registered like the rest of the apps.