Implement initial support of leveldb

- Implement initial support of leveldb database backend
- Fix bugs with leveldb like double opening of database

Open-webOS-DCO-1.0-Signed-off-by: Maksym Sditanov <msditanov@luxoft.com>

Change-Id: Iafb775b256de06f5beceb060c683effcb983982f
Implement transaction logic for leveldb

- Implement fixes for transaction logic
- Add configuration section to configuration file

Open-webOS-DCO-1.0-Signed-off-by: Maksym Sditanov <msditanov@luxoft.com>

Change-Id: I409adff8e28b8efad2c8f2bf9f88d48ad9a2acbb
Remove regression in MojVector (GF-3399)

In MojVector regression in code (fix correction of removed size of elements)

Open-webOS-DCO-1.0-Signed-off-by: Maksym Sditanov <msditanov@luxoft.com>

Change-Id: I9f1346c8c4e243f3fa216da7aa246606d0a733fb