Unit test for connection-validation using a Custom Validator.

The Validator tries to get the number of rows in a dummy table to compare with a count. 

Iteration 1:
Appclient first calls an ejb method to initialize the connection pool.

After first call to ejb, database is restarted.

Iteration 2:
Appclient calls the same ejb method. Since all the connections in the pool is
bad, and validation is not enabled, ejb call must throw exception or return false.

Enable validation.

Iteration 3:
Appclient calls the same ejb method. With validation on, all bad connections are
removed and newly created.

database is restarted.

Iteration 4:
Appclient calls the same ejb method. With validation on, pool must be cleaned
and filled with new resources