Provide more meaningful VM names for services/modules

When running multiple services/modules, there is no indication which VM corresponds to a service.

We may be able to use JDI to invoke `ApiProxy.getCurrentEnvironment().getModuleId()` to get the service name (com.google.apphosting.api.ApiProxy) or [`ModuleService#getCurrentModule()`](https://cloud.google.com/appengine/docs/java/javadoc/com/google/appengine/api/modules/ModulesService.html#getCurrentModule--), though they may not be available outside of the scope of a request.