Add support for mix-in annotations

[jmgilmour]

I am very interested in using your product. In my project, Jackson is currently being used on the server-side to do serialization/deserialization into json. We'd love to be able to integrate gwt-jackson into our GWT GUI as well.

However, we use mix-in annotations (mostly to @JsonIgnore methods) so that we can keep our POJOs free of serialization-related annotations.

It would be great if gwt-jackson supported mix-in annotations.

Info about mix-in annotaitons can be found here: http://wiki.fasterxml.com/JacksonMixInAnnotations

[nmorel]

I agree, it would be great :)

One way to do it would be to use the configuration class added in issue #6 to give the mixin class and the target class to the compiler via a new method.

[nmorel]

I started to work on it in branch mixin. It was almost done for annotations on type. I'll try to resume the work on it as soon as I find some time.

[nmorel]

Done, you can look at documentation here.