Use NPM 6.x on Node 10.x

[sandermarechal]

Use npm 6.x instead of npm 8.0 when using node 10.x, fixes #294

[mistraloz]

Thx for your PR but please follow instruction at top of each files :
# DO NOT EDIT THIS FILE : Make yours changes in /utils/Dockerfile.*.blueprint)

To apply this change only for node10, please do like that :
{{ if eq "10" $node_version }}@^6.14{{end}}

It's require orbit on your computer.

[sandermarechal]

I have updated the PR and made the change in the blueprint file. After running orbit it make the correct changes to the Dockerfiles, but orbit also removed all the DO NOT EDIT THIS FILE lines. Is that supposed to happen? I have not committed the removal of these lines, just the changes to npm install.

[mistraloz]

Thx for this fix @sandermarechal . The related lines at the top of files are added by sed after obit generate (it's on the Makefiles script). But as you did it's perfect. After checks passed, i will merge it.

PS : if you know another better tool/process to manage template, i take all suggestions.

[sandermarechal]

Thank you. I don't know a better way to manage templates. At least orbit is easy to install, as opposed to node+mustache or something.