Spring Scalatra Bootstrap

This enables users to use Scalatra easily with Spring. By adding a dependency onto this new module scalatra-spring, then users can:

* Have resource servlets automatically registered with the servlet context using the @Path annotation (no need for the ScalatraBootstrap hardcoded file)
* Have dependencies autowired into the resource servlets (using constructor injection or field injection)

A simple example

```
@Component
@Autowired
@Path("/customer")
class CustomerRestServlet(customerDao: CustomerDao) extends ScalatraServlet {

  get("/:id") {
    customerDao.find(params("id"))
  }
}

```

Would register a Customer resource listening on /customer/_id_