DERBY-5840: Clean up compiler warnings introduced by using Java 5 language features

- Clean up deprecation warnings in the tests

- Clean up unchecked conversion warnings in org.apache.derbyTesting.junit

git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/trunk@1482234 13f79535-47bb-0310-9956-ffa450edef68