Extract collection attachable properties

That adds `collectionOptions` which is in the spirit of `modelOptions` and `viewOptions` to simplify the attachment of own properties from the `options` object.

This also can serve as a discussion of whether the `url` should be attachable. I personally don't see any problem with that, since there are no name conflicts, as with the `Model`, but I want to ping @tgriesser and @braddunbar.