(hot fix) fix of two obvious mistakes in jQuery.wikibase.snaklistview

At least one of these would throw some exceptions during normal usage of the new multi-snak
References feature.

* usage of undefined variable
* usage of this where self should be used.
* Also got rid of some pointless 'else' (since a return is used inside of the if block)

- patch set 2: Removed code from wikibase.Entity.js which obviously does not belong to
the change set.

Change-Id: I33f64c5b02073cb70cd71528596782bfe355df7b