internal: Fix caches being orphaned from their directory. After clearing caches, the instances in memory don't have a file-system directory anymore. This means that either caching data would crash the app, or, in the case of baking a site, would make the workers create the directory but collide randomly while doing so at the same time.

syntax: glob
*.pyc
venv
tags
build/lib
build/messages/_cache
build/messages/_counter
dist
docs/_cache
docs/_counter
docs/bower_components
docs/node_modules
piecrust.egg-info
piecrust/__version__.py