NVM support

[LukevdPalen]

This pull enables support for Node Version Manager by specifying a path to the node binary like Ajenti-v already does for virtualenv. Reference:

• https://github.com/creationix/nvm
• https://www.digitalocean.com/community/tutorials/how-to-install-node-js-with-nvm-node-version-manager-on-a-vps