fix(instrumentations/bluebird): fix instrumentation

Author: dszakallas

lib/instrumentations/bluebird.js

@@ -32,17 +32,11 @@ module.exports = {
   instrumentations: [
     {
       path: 'bluebird/js/release/promise',
-      post: function (Bluebird, agent) {
-        var bluebird = Bluebird()
-        return wrapper(bluebird, agent)
-      }
+      pre: wrapper
     },
     {
       path: 'bluebird/js/main/promise',
-      post: function (Bluebird, agent) {
-        var bluebird = Bluebird()
-        return wrapper(bluebird, agent)
-      }
+      post: wrapper
     },
     {
       path: 'bluebird',