filterref - allows for java 8 style lambdas for filters

Unfortunately, annotations in java 8 don't support field refs or other things (yet).

This PR implements "filterRef" - an array of strings in <className>.<fieldName> format for referencing public static final fields commonly created by lambdas.

This allows for this kind of java 8 specific construct:
Definition:
```java
public class MyClass {
    public static final IMessageFilter<LifecycleEvent> ServerStarted = (event, metadata) -> event.phase == Phase.STARTED;
}
```

Use:
```java
    @Handler(filterRefs="my.package.MyClass.ServerStarted")
    public void init(LifecycleEvent e) { System.out.println("HELLO 1 " + e.phase); };
```

I hope you accept. I think it'll make my new Java 8 project a lot shinier :)