Adding new commons library for generic Jersey-Guice utility classes.

[elandau]

Generic Jersey ExceptionMapper with Guice based plugin architecture to allow for context based default exception mapping.

Here's how to add a custom default mapper MyExceptionMapper

new JerseyServletModule() {
    @Override
    protected void configureServlets() {
        Multibinder<CustomThrowableExceptionMapper> mappers = Multibinder.newSetBinder(binder(), CustomThrowableExceptionMapper.class);
        mappers.addBinding().to(MyExceptionMapper.class);

        Map<String, String> params = new HashMap<String, String>();
        params.put(PackagesResourceConfig.PROPERTY_PACKAGES, 
                        "com.netflix.jersey.guice.providers.exception;");

        serve("/*").with(GuiceContainer.class, params);
        binder().bind(GuiceContainer.class).asEagerSingleton();
    }
}