Small update to avoid extra find query.
Updated comment routes queries to use req.comment.
Updated picture routes queries.
Fixed collection comment destroy route function.
Fixed picture route destroy function.
Updated picture comment routes.

Updating a picture's comment does not work.
Do not export Metadata from models file as it will be removed.
Removed unique constraint that generates some DB errors.
Added load functions for all resources.
Removed Metadata model and form.