Direct library messages to context of the calling process

:Release Notes:
Direct library messages to context of the calling process

:Detailed Notes:
- This change introduces two new public APIs to pmloglib.
  One to be used from shared libraries using pmlogging.
  The other one for processes to optionally setup a
  library logging context.

- Minor version number bumped.

- Also removed empty string logging for a default context
  since it is a valid context and makes it clear for log
  parsing and analyzing. It will be logged as <default>
  context.

:Testing Performed:
Tested on the device

:QA Notes:

:Issues Addressed:
[BHV-10] PmLogLib: Add default context prefix for libraries

Open-webOS-DCO-1.0-Signed-off-by: Gayathri Srinivasan <gayathri.srinivasan@lge.com>
Change-Id: Ibf35b414ce3a3dd03e87cccb32ba2e4da859569b
Reviewed-on: https://g2g.palm.com/4763
Reviewed-by: DCO Verification
Reviewed-by: Gayathri Srinivasan <gayathri.srinivasan@lge.com>
Tested-by: Gayathri Srinivasan <gayathri.srinivasan@lge.com>
Reviewed-by: Keith Derrick <keith.derrick@lge.com>