* Start of work to support collections
* remove version_added from base schema
* If a collection, pass that to validate-modules
* clean ups
* Allow version_added in a collection, just make it optional
* Don't traceback on missing doc_fragment
* Don't validate metadata in a collection
* Relocate module validator code and tests.
* Fix validate-modules entry point and imports.
* Fix paths and test entry points.
* Fix up unit tests.
* Fix shebang and execute bit.