Add 2 functions to DB API
- WriteNoCommit : write to DB without commiting the last transaction
- CloseCommit   : commit current transaction before closing DB conn

These two functions will allow us to solve one specific performance problem when we need to open a DB, batch insert a set of records and close the DB afterwords
Add dbid arg to the DBPrivOpen function and make sure that the locks DB is open in NOSYNC mode
Merge pull request #1417 from jeffali/up/master_rc7f_lmdb3

Add 2 functions to DB API