Adds default jax-rs @ exclusions and doclet option `excludeAnnotationClasses'

Method parameters with jax-rs annotations ``@Context`` and ``@HeaderParam``
are excluded from API docs. In addition the doclet option
`excludeAnnotationClasses` takes space-separated fully qualified class
names for other method params to exclude.

e.g. this resource with header-authenticated `Bar` injected

```
@GET
@Path("/foos")
public List<Foo> barsFoos(@Auth Bar bar)
```
Together with this javadoc plugin fragment:
```
<additionalparam>-excludeAnnotationClasses com.yammer.dropwizard.Auth</additionalparam>
```

I'm not entirely enthusiastic about the option name `excludeAnnotationClasses`, if there is a better suggestion (`exclude` ?) I can change it.

Also, I'm not sure if this is the way to go anyway. The example swagger docs still have the non-param parameter in the implementation notes, something similar I suppose could be done here so we don't lose that information:
![image](https://f.cloud.github.com/assets/42975/59446/f2bde918-5bc7-11e2-974e-7d12f3a4b2f0.png)