Resolve "Feature: Send endpoint for attributes"

Closes #38 (closed)

ragconnect.base/src/main/jastadd/Util.jadd

 aspect Util {
   static String ASTNode.capitalize(String s) {
+    if (s == null) return null;
+    if (s.isEmpty()) return "";
     return Character.toUpperCase(s.charAt(0)) + s.substring(1);
   }
   protected T JastAddList.firstChild() { return getChild(0); }