ezmultiupload 6.1.2: the can_upload template fetch function

Added: A template fetch function, fetch( 'ezmultiupload', 'can_upload', hash( 'node_id', $node_id ) ), true when the current user can upload files at the node (expMultiuploadService::canUploadAt()). The administration's node view uses it for its Upload button. Documented in doc/fetch-functions.md.