I have a Gulpfile.js in Visual Studio 2015 RC with a single default task. For some reason it is not showing up in the Task Runner Explorer.
Task Runner Explorer
I had added gulp
I had the same problem and no-one of suggested method works for me. After re-installing NPM Task Runner the problem gone away. You can download latest NPM Task Runner from marketplace in following link.
https://marketplace.visualstudio.com/items?itemName=MadsKristensen.NPMTaskRunner