Added post-publish cleanup for NpmPublishTask.
Added post-publish cleanup for NpmPublishTask.

vinodpanicker/jake,vinodpanicker/jake,cesarmarinhorj/jake,cesarmarinhorj/jake,kedashoe/jake,talves/jake,cesarmarinhorj/jake,jakejs/jake,talves/jake,jakejs/jake,kedashoe/jake,vinodpanicker/jake,talves/jake,kedashoe/jake