installer should be more robust if we already have got a userid called trafodion

[Joshua Liu]

the scenario is to check what installer would do if the 'trafodion' userid already exists.

1. uninstall the trafodion instance
2. check userid trafodion doesn't exist
3. manually create userid trafodion in n003 and n004:
    [root@n003 ~]# useradd -p 'traf123' trafodion
    Creating mailbox file: File exists
    [root@n004 ~]# useradd -p 'traf123' trafodion
    useradd: warning: the home directory already exists.
    Not copying any file from skel directory into it.
4. install trafodion through userid root(run trafodion_install in userid root)
     [root@n003 installer]# ./trafodion_install

***INFO: Trafodion Mods ran successfully.

******************************
TRAFODION START
******************************

/usr/lib/trafodion/installer/..
***INFO: Log file location /var/log/trafodion/trafodion_install_2015-04-21-15-48-06.log
***INFO: Starting Trafodion installer (2015-04-21-15-48-06)
/home/trafodion/daily
***INFO: untarring build file /usr/lib/trafodion/daily/trafodion_server-1.1.0.tgz to /home/trafodion/daily
***INFO: modifying .bashrc to set Trafodion environment variables
***INFO: copying .bashrc file to all nodes
***INFO: copying sqconfig file (/home/trafodion/sqconfig) to /home/trafodion/daily/sql/scripts/sqconfig
***INFO: Creating /home/trafodion/daily directory on all nodes
***INFO: starting sqgen
/usr/lib/trafodion/installer/traf_start: line 186: cd: /sql/scripts: No such file or directory
/usr/lib/trafodion/installer/traf_start: line 187: sqgen: command not found
***ERROR: sqgen failed with RC=127. Check install log file for details.
***ERROR: Error while running traf_start.
***ERROR: Setup not complete, review logs.
***ERROR: Exiting....
You have new mail in /var/spool/mail/root

the installer should give a warning or something else that 'trafodion userid already exists'