Heads up: new test suite class

[Dag H. Wanvik]

Hi,

with the introduction of org.apache.derbyTesting.junit.BaseTestSuite 
(https://issues.apache.org/jira/browse/DERBY-6590), we should 
discontinue explicit use of junit.framework.TestSuite and use 
BaseTestSuite instead, cf. rationale in DERBY-6590.

Thanks,
Dag