[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
[#1795] pass package_type to package new and edit templates
[#1795] add package_type/group_type params to IDatasetForm/IGroupForm.validate
[#1795] fix show+update validate calls
[#1795] add IDatasetForm.resource_form method, allow custom resource forms
[#1795] fix for group_type use in _group_or_org_create
[#1795] belt and suspenders for _resource_form
[#1795] index packages with the right validate call
[#1795] tolerate missing tag_string in package controller
[#1795] pass package_type to read template
[#1795] pass dataset_type to all package render calls