Changes to the metadata format were approved here:
https://github.com/ansible/proposals/issues/54
* Update documentation to the new metadata format
* Changes to metadata-tool to account for new metadata
* Add GPL license header
* Add upgrade subcommand to upgrade metadata version
* Change default metadata to the new format
* Fix exclusion of non-modules from the metadata report
* Fix ansible-doc for new module metadata
* Exclude metadata version from ansible-doc output
* Fix website docs generation for the new metadata
* Update metadata schema in valiate-modules test
* Update the metadata in all modules to the new version
* refactor postgres,
* adds a basic unit test module
* first step towards a common utils module
* set postgresql_db doc argument defaults to what the code actually uses
* unit tests that actually test a missing/found psycopg2, no dependency needed
* add doc fragments, use common args, ansible2ify the imports
* update dict
* add AnsibleModule import
* mv AnsibleModule import to correct file
* restore some database utils we need
* rm some more duplicated pg doc fragments
* change ssl_mode from disable to prefer, add update docs
* use LibraryError pattern for import verification
per comments on #21435. basically LibraryError and touching up its usage in pg_db and the tests.
