add last_modified to Raw pages

All pages must have last_modified. I should probably make this required
somehow...
fix Perldoc app to extend Statocles::App

All apps must extend Statocles::App
coerce strings into paths in Perldoc app

When adding the app to the container, we need to inflate the strings
into the objects we want.
set a default last_modified for Raw pages

last_modified is required, not optional
fix module searching in Perldoc app

The Pod::Simple::Search says not to use limit_re(), but we will anyway.
The glob version is not Do What I Mean enough.
fix internal links to the index module

The index module will always be index.html and never anything else.
add default template for perldoc app

This is the bare minimum the perldoc app needs.

We clearly need to add more stuff like the
Mojolicious::Plugin::PODRenderer.
add perldoc app to the Statocles website