Merge pull request #13 from jonahcohen/webscalesql-5.6.19

Add rocksdb_db_options and rocksdb_default_cf_options sysvars.
Update test results after the last merge
Issue #22: SELECT ... FOR UPDATE takes a long time
- Specify the right column family when making a rocksdb::Get() call.
Add sysvar for specifying file containing column family configs.