www/node6: Update 6.13.1 -> 6.14.0

This is a security release addressing multiple vulnerabilities. Users
are recommended to upgrade as soon as possible.

https://nodejs.org/en/blog/vulnerability/march-2018-security-releases/
https://nodejs.org/en/blog/release/v6.14.0/

MFH: 2018Q1
Security: 5a9bbb6e-32d3-11e8-a769-6daaba161086