Check for a launch configuration's existence.

    CLI example::

        salt myminion boto_asg.launch_configuration_exists mylc

def launch_configuration_exists(name, region=None, key=None, keyid=None,
                                profile=None):
    '''
    Check for a launch configuration's existence.

    CLI example::

        salt myminion boto_asg.launch_configuration_exists mylc
    '''
    conn = _get_conn(region=region, key=key, keyid=keyid, profile=profile)
    retries = 30
    while True:
        try:
            lc = conn.get_all_launch_configurations(names=[name])
            if lc:
                return True
            else:
                msg = 'The launch configuration does not exist in region {0}'.format(region)
                log.debug(msg)
                return False
        except boto.exception.BotoServerError as e:
            if retries and e.code == 'Throttling':
                log.debug('Throttled by AWS API, retrying in 5 seconds...')
                time.sleep(5)
                retries -= 1
                continue
            log.error(e)
            return False