Change EvalResultIterator to implement java.io.Closeable

[hansenmc]

Given the note in the JavaDocs for the ServerEvalIuationCall that the EvalResultIterator must be closed

• NOTE: EvalResultIterator MUST BE CLOSED. If you call {@link #eval()} don't forget to call close() on the returned EvalResultIterator to free up the underlying resources.

it would be useful if EvalResultIterator implemented java.io.Closeable.

If the EvalResultIterator implemented Closeable, it would be possible to use try-with-resources to ensure that it is automatically called, and a bunch of finally blocks could be removed for cleaner and more simple code.

[sammefford]

Ajit, I made sure EvalTest runs w/out problem. If regression runs fine, I think we can ship this.