comments endpoints depend on filesystem and metadata
all comments logic moved from routes.comments to services.metadata.comments
moved entry-accessible? function

This function was move to more appropriate namespace donkey.services.filesystem.exists.
moved validate-entry-accessible function

This function was move to more appropriate namespace donkey.services.filesystem.uuids.
moved logic unrelated to routing to services

The logic unrelated to routing was moved from donkey.routes.favorites to donkey.services.metadata.favorites.
favorites routes now depend on filesystem being enabled.
documented favorites
tags routes now depends on filesystem being enabled.
all business logic for tags moved to services.metadata.tags
documented tags logic