w3af, nodejs and vscode-server with better build process!

It improves the build process to optimize the image creation, minimizing the number of layers and the resultant image size.

Also deploys the following new tools:

• w3af (dropped out of Kali repos)
• code-server
  • exposing tcp/8443 to the host
• nodejs 11, npm and yarn (from nodejs repos)

See #4