Fix ctor instanceof guard

The ! operator is higher priority than the instanceof operator, so the
expression (! this instanceof X) is the same as ((!this) instanceof X),
which will always evaluate to false.

lib/bunyan.js

@@ -233,7 +233,7 @@ function resolveLevel(nameOrNum) {
  */
 function Logger(options, _childOptions, _childSimple) {
     xxx('Logger start:', options)
-    if (! this instanceof Logger) {
+    if (!(this instanceof Logger)) {
         return new Logger(options, _childOptions);
     }