Fix parent 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

@@ -242,7 +242,7 @@ function Logger(options, _childOptions, _childSimple) {
     if (_childOptions !== undefined) {
         parent = options;
         options = _childOptions;
-        if (! parent instanceof Logger) {
+        if (!(parent instanceof Logger)) {
             throw new TypeError(
                 'invalid Logger creation: do not pass a second arg');
         }