Replace "can not" with "cannot"

src/jastadd/ast/Attributes.jrag

@@ -869,7 +869,8 @@ public aspect Attributes {
             buf.append("\\b)");
             pattern = buf.toString();
           }
-          String newContents = "refined_" + original.aspectName() + "_" + name() + "_" + methodName;
+          String newContents = String.format("refined_%s_%s_%s",
+              original.aspectName(), name(), methodName);
           // TODO: update keep to false if no strings are replaced.
 
           Matcher matcher = Pattern.compile(pattern).matcher(s);