remove the flicker on drop

Ok. So it turns out that removing the flicker on
drop was relatively straight forward.  Avoid putting
the thing back where it was, so we don't re-re-render.

src/dragula-and-drop.js

@@ -47,8 +47,8 @@ export class DragulaAndDrop {
       invalid: this._invalid.bind(this)
     };
 
-    let options = Object.assign(aureliaOptions, boundOptions);
-    this.dragula = new Dragula(options);
+    this.options = Object.assign(aureliaOptions, boundOptions);
+    this.dragula = new Dragula(this.options);
 
     this.dragula.on('drop', this._dropFunction.bind(this));
 
@@ -88,7 +88,7 @@ export class DragulaAndDrop {
   }
 
   _dropFunction(item, target, source, sibling, itemVM, siblingVM) {
-    this.dragula.cancel();
+    this.dragula.cancel(this.options.revertOnSpill, true);
     if (typeof this.dropFn === 'function')
       this.dropFn({ item, target, source, sibling, itemVM, siblingVM });
   }