Adds a template to handle reworking the default configuration.

The difference over the default is (for now) the root.
Adds Nginx to the Vagrantfile run list.
Switches out the variable use for the default template.

It's possible that it won't be available. I didn't test it.
Moves the default-site template into a defaults folder.
Implements the ability to dynamically render error pages.
Adds attributes to configure the footer text.
Documents the attributes.
Adds a 500 error handler.
Adds a configuration to enable the error handlers.