install nvm in udumbu

apt-get update
apt-get install build-essential libssl-dev

curl https://raw.githubusercontent.com/creationix/nvm/v0.25.0/install.sh | bash

Ref:
https://github.com/creationix/nvm/releases (see version latesT)
Ref: https://www.liquidweb.com/kb/how-to-install-nvm-node-version-manager-for-node-js-on-ubuntu-12-04-lts/
Ref:
https://www.sitepoint.com/quick-tip-multiple-versions-node-nvm/