(Bug 19487) Fix predefined property annotation for file upload

Even though it is called Semantic-Media-Wiki, media 'file' upload annotation has been broken since 2009.

As for the original Bug [0], predefined properties are now correctly updated whenever a new upload takes place and moreover MEDIA and MIME are now set automatically (if configuration enables it).

Relates to #162

[0] https://bugzilla.wikimedia.org/show_bug.cgi?id=19487