Provide Ant task for launching Jetty

We could use a clean, easy way of launching Jetty using a custom Ant task.

This task would essentially use Jetty's embedding API, but configured using properties and structures defined within the Ant script itself, rather than a seperate XML file.

Off the top of my head, something simple like:

{{
<jetty:startup port="8888">
<webapp location="/my/webapp/dir"/>
<webapp location="/my/other/webapp/dir"/>
</jetty:startup>
}}

This stuff is easy enough to implement, but it would be great if jetty provided it out of the box.