Merge pull request #223 from salmanhasni/salman-220-set-document-fix

fixes #220 changed .remove hashMap to .delete

lib/client/ground.db.js

@@ -221,7 +221,7 @@ Ground.Collection = class GroundCollection {
   setDocument(doc, remove) {
     doc._id = strId(doc._id);
     if (remove) {
-      this._collection._docs._map.remove(doc._id);
+      this._collection._docs._map.delete(doc._id);
     } else {
       this._collection._docs._map.set(doc._id, EJSON.clone(doc));
     }