Switch webstats_js setting from site_properties to p.a.registry.

Conflicts:
	plone/app/layout/analytics/tests/analytics.txt
	plone/app/layout/analytics/view.py
	plone/app/layout/globals/portal.py
	plone/app/layout/globals/tests/test_portal.py
	plone/app/layout/sitemap/tests/test_sitemap.py