Add support for plugin REST endpoints without view names

With this change it is possible to bind REST endpoints in plugins with empty
view names:

  @Override
  protected void configure() {
    install(new RestApiModule() {
      @Override
      protected void configure() {
        delete(REVISION_KIND).to(HelloWorldAction.class);
      }
    });
  }

So defined endpoint can be accessed in two ways: with and without plugin
namespace:

 DELETE /changes/1/revisions/1/
 DELETE /changes/1/revisions/1/cookbook~

The last case is important to support because UiActions always prefix the view
name with the plugin name.

Change-Id: Ifd32fd7f33edcc7fcf763cdd780fb0a95e111519
1 file changed