[145] Manual cherry-pick of bits of 0e687a102 relevant to ONS.
[145] ONS importer - ons_merge_duplicates.py for tidying up ONSHUB datasets. Only sysadmins can now edit ONSHUB datasets. Add mapping for 2 new publisher names discovered.

Conflicts:

	ckanext/dgu/theme/templates/package/edit.html
	ckanext/dgu/theme/templates/package/new.html
[145] ONS importer - Resource now stores publish date and resources are sorted by this now. Logging names item GUID and date.
[145] ONS importer - merger tool was partially disabled.