Fix bugs and minor adjustment for RHEL6

1. Remove setthreadtitle() function invoking in masterchief and
cortana.php because that function is part of PECL package. It's better
to use the php built-in function cli_set_proc_title(), but it's only
supported after php 5.5. Hence, we wait.

2. Because we don't change process title now. We change the description
format for worker in log to 'Worker(PID=XXXX)'.

3. Because we use su and sudo command combination to exec the job which
provide native sudo checking mechanism, we don't have to check sudo
privillege on our own again. Hence, we remove sudo check part in method
authentication_job in class mc_daemon.