Add API for db compact

:Release Notes:
Add leveldb compacting call for every purge.

:Detailed Notes:
Add missing API functions for use leveldb compacting.
MojDbLevelDatabase::compact use LDB::CompactRange.

:Testing Performed:
tested on local build

:QA Notes:
run script attached to ticket

:Issues Addressed:
[BHV-1276] Partition full error

Open-webOS-DCO-1.0-Signed-off-by: Igor Kuksyuk <igor.kuksiuk@lge.com>

Change-Id: I78667d0bb48baf08c89d46108e1ba24384238916
Reviewed-on: https://g2g.palm.com/4857
Reviewed-by: DCO Verification
Reviewed-by: Igor Kuksyuk <igor.kuksiuk@lge.com>
Tested-by: Igor Kuksyuk <igor.kuksiuk@lge.com>
Reviewed-by: Oleg Yablokov <oleg.yablokov@lge.com>
Reviewed-by: Maksym Sditanov <maxim.sditanov@lge.com>