Patch to add a new loglevel(OFF) to turn off logging

Hi,

As discussed before, adding a new loglevel explicitly
to turn off logging may be useful sometimes.

For example:
Driver.setLogLevel() ;//open a JVM level's logging
con = DriverManager.getConnection(connectionString)//want to turn off logging in this Connection

or
Driver.setLogLevel() ;//open logging
//do something
Driver.setLogLevel() ;//want to turn off logging
//do other things


And I have wrote a simple patch for that,
Hopefully this useful.

*)if be accepted,document about loglevel should be updated

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Best Regards,
Chen Huajun