Improve JSON schema validation performance

:Release Notes:
Generic singleton validators for basic types is used if there is no need
to keep validation information to increase validation speed and reduce
memory usage in certain cases.

:Detailed Notes:
All specific features of validators (properties, default values etc.)
are now applied by validator = feature_apply(validator, feature)
signature which automatically create new instance of validator to store
feature if needed.
Separate type for integer validator is used during schema parsing to
indicate type independently of validator inner structure

:Testing Performed:
Unit test with valgrind

:QA Notes:

:Issues Addressed:
[GF-42811] pbnjson: Implement more static objects to improve memory
           footprint

Open-webOS-DCO-1.0-Signed-off-by: Mykola Kryvonos <mykola.kryvonos@lge.com>

Change-Id: If2387385fbe5d9d34f293be3cf2ee4082e98b654
Reviewed-on: https://g2g.palm.com/3633
Reviewed-by: Build Verification
Reviewed-by: Mykola Kryvonos <mykola.kryvonos@lge.com>
Tested-by: Mykola Kryvonos <mykola.kryvonos@lge.com>
Reviewed-by: Anatolii Sakhnik <anatolii.sakhnik@lge.com>