Allow the Wikipedia extension to resize original images

[bartfeenstra]

Allow the Wikipedia extension to realize original images before saving them to disk and creating File entities for them. This allows site owners to control maximum (file) size, which impacts their sites' size, and bandwidth, and traffic needs. For Betty itself, this would allow prebuilding the demo site while keeping the max asset size somewhat under control.

Maybe better: set a global setting for the filters, and apply those even when just copying originals (if the setting is enabled)