npm security audit needs dealing with

[AaronNGray]

$ npm install
audited 6729 packages in 4.727s
found 16 vulnerabilities (7 low, 3 moderate, 5 high, 1 critical)
run npm audit fix to fix them, or npm audit for details

[TimvdLippe]

This is a duplicate of Polymer/tools#428 We are working on it.