Start the specified service

    CLI Example:

    .. code-block:: bash

        salt '*' service.start <service label>
        salt '*' service.start org.ntp.ntpd
        salt '*' service.start /System/Library/LaunchDaemons/org.ntp.ntpd.plist

def start(job_label, runas=None):
    '''
    Start the specified service

    CLI Example:

    .. code-block:: bash

        salt '*' service.start <service label>
        salt '*' service.start org.ntp.ntpd
        salt '*' service.start /System/Library/LaunchDaemons/org.ntp.ntpd.plist
    '''
    service = _service_by_name(job_label)
    if service:
        cmd = 'launchctl load -w {0}'.format(service['file_path'], runas=runas)
        return not __salt__['cmd.retcode'](cmd, runas=runas, python_shell=False)

    return False