Added dropwizard-embedded module, to embed a service in a daemon

This new module adds a new interface to a Dropwizard HTTP(s) service, so
that the HTTP server can be started/stopped at any point within an
already existing daemon process (no CLI required). This allows a
developer to embed Dropwizard into already existing services with their
own main run loop and SLF4J logging infrastructure.

Code example:
```java
public class WebService extends io.dropwizard.embedded.Service<Configuration> {
    public void initialize(EmbeddedBootstrap<Configuration> bootstrap) {
        // add bundles
        bootstrap.addBundle(new ViewBundle());
    }
    protected void start(Configuration config, Environment env) {
        // add resources
        env.jersey().register(new HelloWorldResource());
    }

    public static void main(String ... args) {
        handleCommandLine(args);
        configureSlf4jLogging();
        start();
        new MainRunLoop().run();
        stop();
    }
}
```
Where is this logback file used? Also, when the parent process starts and configures logging, won't the embedded service override the logging settings with what's in the LoggingFactory defined in the DW configs?