I have been lazy to keep using sudo with all NPM global installs on Ubuntu 14.04 and today I finally browsed for the simple solution and applied it and it is fixed for all. Posting here for future reference for me and you 🙂
Here is Help Link:
Here is Video
I used first option i.e. Change permissions to /usr/local dir. Thanks to awesome community members of NodeJs for having this simple guide to fix issue of NPM Permissions error whenever installing any global module.