WikibaseClient uses __FILE__ instead of __DIR_

By using __FILE__ the path will be wrong and the link is not
generated on Special:Version. This is done already in WikibaseLib
and Wikibase.

Change-Id: I9c37ab4a5aeb1aaf7b8bced855ce0ca7c329a94a
Merge "WikibaseClient uses __FILE__ instead of __DIR_"