New Permission management module

There is a new permission management module placed in the plugins folder:

    plugins/modules/ipapermission.py

The permission module allows to ensure presence of absence of permissions
and manage permission members.

Here is the documentation for the module:

    README-permission.md

New example plabooks have been added:

    playbooks/permission/permission-absent.yml
    playbooks/permission/permission-allow-read-employeenum.yml
    playbooks/permission/permission-member-absent.yml
    playbooks/permission/permission-member-present.yml
    playbooks/permission/permission-present.yml
    playbooks/permission/permission-renamed.yml

New tests for the module:

    tests/permission/test_permission.yml