add tidb driver

[knull-cn]

1. driver repo : https://github.com/pingcap/tidb-loadbalance
   it will be load balance by driver , by it is dependent on mysql-driver
   use load balance can go to the repo; and tomcat has bug and should set tidb.jdbc.url-mapper = random (default is robin but was not effective)

2. you can run tpcc on tidb database with this command
   sql file is same to mysql, so use mysql/*.sql file
   props.tidb was difference to props.mysql, which is changed driver and the conn values.
   create database tpcc;

cd run && 
./runSQL.sh props.tidb sql.mysql/tableCreates.sql && \
./runSQL.sh props.tidb sql.mysql/indexCreates.sql
./runLoader.sh props.tidb

./runBenchmark.sh props.tidb 

3. of course, you can also use mysql driver to connect tidb