Add option to silence the standard outputs

:Release Notes:
The option "-s" is added.

:Detailed Notes:
Every PmLogCtl commands accept options "-s" to silence
standard error outputs. This allows shell scripts to prevent
messages such as "context already exists" from polluting the
console log.

:Testing Performed:
Compiled locally and tested on local and TV.
Verified in the log file, error text displayed in
/var/log/messages properly.

:QA Notes:

:Issues Addressed:
[GF-13241] pmlogctl: Provide an option to silence the printf ...

Open-webOS-DCO-1.0-Signed-off-by: Hongjeon Ha <hj.ha@lge.com>

Change-Id: Ic3f2f953f492c702a4a67bd705d91cd650e19962
Reviewed-on: https://g2g.palm.com/3080
Reviewed-by: Build Verification
Reviewed-by: Keith Derrick <keith.derrick@lge.com>
Reviewed-by: Hongjeon Ha <hj.ha@lge.com>
Tested-by: Hongjeon Ha <hj.ha@lge.com>
Reviewed-by: Gayathri Srinivasan <gayathri.srinivasan@lge.com>