Fix Eclipse compiler warnings

I've split the various fixes into separate commits to illustrate why/how I fixed certain warnings.
Did some research. I believe giving the class with an explicit `serialVersionUID` would prevented some kinds of problems, like the generated ID being changed due to trivial changes in the class. It wouldn't have helped us in cases where a new field was added, and might not have helped us in cases were the fields were renamed. If we had an explicit ID set in one release, and renamed the fields in follow-up release without changing the ID, I believe serialization would have still failed.

If we have Eclipse generate one, I believe they would match what the JVM would have generated, but this SO answer states otherwise: http://stackoverflow.com/a/285809

I would rather leave these warnings in (not suppressed). We could add an issue for someone to add serial version IDs to these classes that match the IDs in the previous jars (perhaps testing it in a similar way that I tested my serialization fix)