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.