DataBase.OracleClient is available.
This class could read the tnsnames.ora file to get the definition of the connection.
It takes the serverName as the file path. If null, it will try to read $ORACLE_HOME/network/admin/tnsnames.ora by default.
Also it takes catalog as the tns identifier. If null, it will try to read the $ORACLE_SID environment variable by default.
The port parameter does not affect anything by now.

Signed-off-by: 核心力量 <kernelforce@gmail.com>