bump nodejs versions 10.15.2, 8.15.1, 6.17.0

[falkzoll]

• Security updates
  • https://nodejs.org/en/blog/release/v10.15.2/
  • https://nodejs.org/en/blog/release/v8.15.1/
  • https://nodejs.org/en/blog/release/v6.17.0/