MojDbTxnTest added to test transactions isolation

- parallel transactions should not see uncommited data
- transaction roll-back should keep original database intact

Note that BerkeleyDB engine doesn't allow parallel transaction by some
reasons. That's why it was disabled for it.

Open-webOS-DCO-1.0-Signed-off-by: Nikolay Orliuk <norluk@luxoft.com>
Change-Id: I8a58bdb1be68cf47028789f95dd47a370674745a
Reviewed-on: https://g2g.palm.com/2224
Reviewed-by: Build Verification
Reviewed-by: Nikolay Orliuk <norluk@luxoft.com>
Tested-by: Nikolay Orliuk <norluk@luxoft.com>
Reviewed-by: Maksym Sditanov <msditanov@luxoft.com>
Reviewed-by: Roger Stringer <roger.stringer@lge.com>