Fix Node container errors

[lbassin]

This PR resolves #28

I changed default command of the node container and add missing packages
With this PR we'll be able to successfully build our js and scss

[cgrandval]

@lbassin I prefer to put dockerfile files in a docker directory too (@tdutrion doesn't agree, I think). So, a little comment to decide definitively what is our final decision as it's not the case for now with the other php dockerfile

[cgrandval]

I have this error

node_1 | yarn install v1.12.1
node_1 | info Visit https://yarnpkg.com/en/docs/cli/install for documentation about this command.
node_1 | error install has been replaced with add to add new dependencies. Run "yarn add && yarn encore dev" instead.

[cgrandval]

If I use the node:latest image (in the docker-compose.yml), everything's fine for me. Perhaps, it's better to change the tag of the node image we're using. What do you think @lbassin ?

[lbassin]

I agree to use node:latest, this tag is just bigger but it shouldn't be an issue in this case

What should we do about others dockerfile ?
Do we move them to a docker folder to keep a clean and structured root folder ? In this case, i think it should be done in another PR

[cgrandval]

I agree to put everything in a docker folder. I think Delphine did that but @tdutrion asked her to put everything at the root. Don't know why :-)

[lbassin]

Considering this subject isn't related to the node container i am going to open an new issue to talk about it

We can merge this PR if everything is ok for you @cgrandval

Changes accepted