Get hostname from replication cache group

    CLI example::

        salt myminion boto_elasticache.get_group_host myelasticachegroup

def get_group_host(name, region=None, key=None, keyid=None, profile=None):
    '''
    Get hostname from replication cache group

    CLI example::

        salt myminion boto_elasticache.get_group_host myelasticachegroup
    '''
    conn = _get_conn(region=region, key=key, keyid=keyid, profile=profile)

    if not conn:
        return None
    try:
        cc = conn.describe_replication_groups(name)
    except boto.exception.BotoServerError as e:
        msg = 'Failed to get config for cache cluster {0}.'.format(name)
        log.error(msg)
        log.debug(e)
        return {}

    cc = cc['DescribeReplicationGroupsResponse']['DescribeReplicationGroupsResult']
    cc = cc['ReplicationGroups'][0]['NodeGroups'][0]['PrimaryEndpoint']
    host = cc['Address']
    return host