Configuration of autostarted bundles

Currently only preconfigured bundles are marked with `start` flag in the `config.ini`. I neede to mark some custom plugins (webconsole and jetty) as autostarted too. I extended the gradle script configuration with an `autostartedBundles` property:
````
    products {
        autostartedBundles << 'org.eclipse.equinox.http.jetty'
        autostartedBundles << 'org.apache.felix.webconsole'
    }
    run {
        autostartedBundles.addAll(products.autostartedBundles)
    }
````
Maybe the definition of the default  ones (`org.eclipse.core.runtime`, `jersey-core`) could be extracted to `RunExtension` and `EquinoxAppProductsExtension`, but quite frankly I'm not sure if its the right place.