* Platform agnostic net_system module
Also refactor the action network plugins for better code re-use
Still more refactoring to do once the connection plugin work is complete
* Replace importlib for imp
importlib is not available on 2.6, so we need to stick to imp
* Load action plugin via module metadata
* Better error message if no implementation is found
Now the plugin will show the module name and the network OS in the
error message
* Fix typo on documentation author line
* Fix pep8 issues
* Add missing options key on doc string and stringify version
* Return None in case module has no metadata
* Read module metadata only if it's a python module
Check for module suffix, if it's .py then read metadata.
Otherwise this fails on non-python modules, like Windows PS for example.
* Read metadata variable only if it's a python module
Fix referencing a variable before assignment
* Add action_handler to validate_modules metadata schema
* Pull metadata with plugin_docs get_docstring
Using load_source from PluginLoader is troublesome, it is not guaranteed
a module may be importable at the controller, e.g. if a module depends
on module_utils functions it won't work, because module_utils is not
in the sys path.
Rather than putting that module dependencies introspection, just
use plain parsing like plugin_docs get_docstring does as we only care
about reading ANSIBLE_METADATA.
* Add platform agnostic group of groups for integration tests
This will be the target for platform agnostic integration tests.
* Add integration tests for net_system
* Switch to action plugin inheritance from metadata driven action handler
As the metadata action driven action handler work is being worked on
on its standalone proposal+PR, let's just go back to have one
action handler per platform agnostic module.
Those action plugins will inherit from net_base.
* Add blank line to fix pep8
* Add aliases file to net_system integration test
This will avoid CI failure
* Fix integration tests for net_system
* Give more precedence to task network_os over inventory network_os
