"get" appearing in property names with 2.6.x

Filed from discussion with @christophercurrie in #217.

Here's a possible pattern (not 100% sure). I think using `@JsonProperty` without a value is causing this. I've confirmed that the issue goes away when I don't register the Scala module.

I'm building JSON for a class named `Product`. `@JsonAutoDetect` is set up on `Surface` so nothing is autodetected so I have to whitelist properties with `@JsonProperty`.

``` java
@JsonAutoDetect(creatorVisibility = JsonAutoDetect.Visibility.NONE,
fieldVisibility = JsonAutoDetect.Visibility.NONE,
getterVisibility = JsonAutoDetect.Visibility.NONE,
isGetterVisibility = JsonAutoDetect.Visibility.NONE,
setterVisibility = JsonAutoDetect.Visibility.NONE)
public interface Surface { ... }

public abstract class AbstractSurface implements Surface { ... }

public class Product extends AbstractSurface implements Comparable { ... }
```

Some of my properties come from `AbstractSurface` and other come from `Product`, but I think that the ones that have the unexpected `get` prefix have `@JsonProperty` without a value.

Sorry, no test case right now but hopefully that points you in the right direction.