Added CustomDataTable which calls toJSON JSNI function for caching

Author: timeu

src/main/java/at/gmi/nordborglab/widgets/geneviewer/client/datasource/CustomDataTable.java

@@ -0,0 +1,12 @@
+package at.gmi.nordborglab.widgets.geneviewer.client.datasource;
+
+import com.google.gwt.visualization.client.DataTable;
+
+public class CustomDataTable extends DataTable {
+	
+	protected CustomDataTable() {}
+	
+	public final native String toJSON() /*-{
+		return this.toJSON();
+	}-*/;
+}