New delegation management module

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

    plugins/modules/ipadelegation.py

The delegation module allows to ensure presence and absence of delegations
and manage delegation attributes.

Here is the documentation for the module:

    README-delegation.md

New example playbooks have been added:

    playbooks/delegation/delegation-absent.yml
    playbooks/delegation/delegation-present.yml
    playbooks/delegation/delegation-member-absent.yml
    playbooks/delegation/delegation-member-present.yml

New tests for the module:

    tests/delegation/test_delegation.yml