Get the policy for the specified key.

    CLI example::

        salt myminion boto_kms.get_key_policy 'alias/mykey' mypolicy

def get_key_policy(key_id, policy_name, region=None, key=None, keyid=None,
                   profile=None):
    '''
    Get the policy for the specified key.

    CLI example::

        salt myminion boto_kms.get_key_policy 'alias/mykey' mypolicy
    '''
    conn = _get_conn(region=region, key=key, keyid=keyid, profile=profile)

    r = {}
    try:
        key_policy = conn.get_key_policy(key_id, policy_name)
        r['key_policy'] = salt.serializers.json.deserialize(
            key_policy['Policy'],
            object_pairs_hook=odict.OrderedDict
        )
    except boto.exception.BotoServerError as e:
        r['error'] = __utils__['boto.get_error'](e)
    return r