Improve performance in json stream parsing

:Release Notes:
Add yajl_dont_validate_strings for Yajl 2.
Custom simple memory pool.
Throughput measurement in MBps.
Add pool of dom parsers.

:Detailed Notes:
Add yajl_dont_validate_strings for Yajl 2.
Memory pool gives us a big win in performance.
Fix performance tests to measure the throughput in MB/s.
Some small improvements and code refactoring.

:Testing Performed:
gtest

:QA Notes:

:Issues Addressed:
[BHV-123] pbnjson: Improve performance of json parsing with YAJL

Open-webOS-DCO-1.0-Signed-off-by: Andrii Zora <andrii.zora@lge.com>

Change-Id: Ic2b49103cf438c77e48f961258e9842fd84fb7d0
Pbnjson: precision with numbers in schema validation

:Release Notes:
Fix potencial overflow issue

:Detailed Notes:
There is no needs to use gmp_printf instead of sprintf.
Fix potencial bug.
Make a little test modification of double type.

:Testing Performed:
Gtest

:QA Notes:

:Issues Addressed:
[BHV-1559] Use gmp_printf() instead of sprintf() to increase precision
with numbers

Open-webOS-DCO-1.0-Signed-off-by: Andrii Zora <andrii.zora@lge.com>

Change-Id: Iacb6417f9d4fff3f2ad90535d09410d7738c83c5
Merge branch 'master' of ssh://g2g.palm.com:29418/libpbnjson

Open-webOS-DCO-1.0-Signed-off-by: Andrii Zora <andrii.zora@lge.com>