[1407] WIP - Remove resourcegroups.

Contains a migration to remove the resourcegroups and have the resource
have a reference direct to it's package, this removes a lot of joins.

Drop constraint on resource_group_revision that travis complains about (but local install does not)
Minor tweaks, need completing
Put the test core back how it should be
Merge conflict
[1407] WIP - Remove resourcegroups.

Contains a migration to remove the resourcegroups and have the resource
have a reference direct to it's package, this removes a lot of joins.

Drop constraint on resource_group_revision that travis complains about (but local install does not)
Minor tweaks, need completing
Put the test core back how it should be
Merge branch '1407-remove-resourcegroups' of github.com:okfn/ckan into 1407-remove-resourcegroups

Conflicts:
	ckan/logic/action/get.py
	ckan/logic/schema.py
	ckan/model/resource.py
Test fixes for removing resource groups, stuck in test_dictization where the resource in expected package cannot know the package_id
More passing tests
MERGE from master
Changes to make the tests pass
Fix for the datastore tests
Merge branch '1407-remove-resourcegroups' of github.com:ckan/ckan into 1407-remove-resourcegroups
[#1407] Fix for resource_delete auth and added tests.
Merge pull request #1443 from ckan/1407-remove-resourcegroups

#1407 Remove resourcegroups.