Return all installed services

    Returns:
        list: Returns a list of all services on the system.

    CLI Example:

    .. code-block:: bash

        salt '*' service.get_all

def get_all():
    '''
    Return all installed services

    Returns:
        list: Returns a list of all services on the system.

    CLI Example:

    .. code-block:: bash

        salt '*' service.get_all
    '''
    services = _get_services()

    ret = set()
    for service in services:
        ret.add(service['ServiceName'])

    return sorted(ret)