Fix socket/memory leak bug in relex.Server

According to Dr. Vepstas, [in certain cases current RelEx leaks 10 GB/day](https://github.com/opencog/relex/blob/7ef54f83d81d093955ca15db322ec010bd3f1745/src/java/relex/Server.java#L417).

I've found 2 potential causes that can be fixed, which Eclipse happily informs:

1. ![relexleak1](https://cloud.githubusercontent.com/assets/24123/3553858/f0e4d478-0907-11e4-84a2-fe7fbb501ec7.png)
2. ![relexleak2](https://cloud.githubusercontent.com/assets/24123/3553861/f7785864-0907-11e4-8b9c-f1c58ba0282e.png)

This is done in Java5, however the Java7/8 version would be much simpler and more compact.