(minor) Introduced new base widget for template based widgets

Introduced jQuery.TemplatedWidget which can be used for widgets based on any template coming from mw.template. Adjusted all jquery.wikibase widgets using a template to use this base widget.

Change-Id: Iaa758b2152b1f01459c218ca61e2f3894bd25e11
Merge "(minor) Introduced new base widget for template based widgets"