* Get accurate reason when a query is not executed sucessfully. Disable test case for async query in lua51 connector.
* Add a build option to disable embedded lua lib. By default enable.
* Restore default dependency for module query to avoid compile error on windows.
* Add support for async query. Only insert result is parsed.
* Add support for connection pool.
* Add one case for lua connector in smoke test case list.
* Build dymanic library for lua connector before smoke test.
Connector is implemented by lua51 but luajit and ffi are not included. Connection pool is not implemented yet. It is a raw demonstration at present and not verified on production environment.