Throw 404 for non-existent org for bulk_process

Fixes #1682
[#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
[#1817] Upgrade SQLAlchemy to 0.9.x

No changes needed in the CKAN code base, but it requires changes on vdm,
see this branch:

https://github.com/okfn/vdm/tree/sqlalchemy-0.9-support

Also upgraded sqlalchemy-migrate.
[#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
[#1795] fix dataset_type passing in resource templates
[#1795] use dataset_type parm name in new plugin interface
[#1795] remove long-deprecated method of overriding package form
[#1795] remove long-deprecated method of overriding package form, second instance
[#1795] deprecate use of {{ c.form | safe }} in package templates
[#1795] use h.snippet for forms in package templates (not two render() calls)
[#1795] fix for genshi templates
[#1795] remove dead code