Removed unnecessary nodes from "wb-statement" template

Simplifying the statement node structure by removing nodes that have no actual use.
This allows dropping the toolbarParentSelector option for statementview "edit" toolbar
as wells as for the references "add" toolbar.

Change-Id: I0376ed6c2f885d4b2915a6db7a297d270d6c98ce
Merge "Removed unnecessary nodes from "wb-statement" template"