Fix declaratations and dicovery of levelbd/db.h

Use #include <leveldb/db.h> instead of #include "leveldb/db.h"
Change logic to find include folder with leveldb/db.h

Open-webOS-DCO-1.0-Signed-off-by: Roger Stringer <roger.stringer@lge.com>

Change-Id: If90e721c6a85cdcbe6944f215c3aefe667d2530c
Reviewed-on: https://g2g.palm.com/2700
Reviewed-by: Build Verification
Tested-by: Roger Stringer <roger.stringer@lge.com>
Reviewed-by: Igor Kuksyuk <ikuksyuk@luxoft.com>
Tested-by: Igor Kuksyuk <ikuksyuk@luxoft.com>
Reviewed-by: Roger Stringer <roger.stringer@lge.com>