(bug 44538) Simple counter for statementview's references

* Counter will update whenever a new source has been saved or removed
* Changed 'wikibase-statementview-referencesheading' message and qqq back to its 92fe330 version

- patch set 3: rebase

Change-Id: I8c3a06b70a3f58921353a57a8e328b457d46a1cc