Adapt to new JavaScript datamodel and serialization

Needs
* https://github.com/wmde/WikibaseDataModelJavascript/pull/16
* https://github.com/wmde/WikibaseSerializationJavaScript/pull/6

Bug: 72757
Change-Id: Iafc2ed96df9f4a36b87ea9217eddc653fd3c4b9c
Applied key handling to referenceview edit toolbar

Change-Id: Icb827b212629b9d16a6f936e9b76579c4d7e798b
Merge "Applied key handling to referenceview edit toolbar"