Clear TransactionTable's reaper thread TCCL on shutdown

Module deployment's classloader is being leaked in TransactionTable's reaper thread. This image comes from a modified version of 5.2.x but it looks like it might be a problem in 5.3.x as well.

![class-loader](https://f.cloud.github.com/assets/1113687/621861/cd7bd080-cf1b-11e2-96b6-0129fcac8346.png)