diff -r 19f0b7803aed -r b38cf3d4cf1f client/js/models.js
--- a/client/js/models.js	Fri May 29 14:57:37 2015 +0200
+++ b/client/js/models.js	Mon Jun 01 11:53:03 2015 +0200
@@ -296,6 +296,7 @@
         },
         toJSON : function() {
             var json = _.clone(this.attributes);
+            delete json.schemaVersion;
             json.schema_version = this.schemaVersion;
             for ( var attr in json) {
                 if ((json[attr] instanceof Backbone.Model) ||