Install some npm libraries as devDependencies

[ohbarye]

Hello maintainers.

When I tried to use some installers, I found that some of npm libraries which should locate in devDependencies are in dependencies section in package.json.

So I just tweaked the installation scripts.

[javan]

I believe these are needed as dependencies for compiling on the server (aka deploying).

[gauravtiwari]

Thanks @javan

Yeah, please see this PR #117 and related issue for more info.

[gauravtiwari]

Ahh I think elm-hot-loader can be under devDepencies so if you wanna update the PR with only that change I am happy to merge, thank you 👍

[ohbarye]

@javan @gauravtiwari
I didn't know the background and now understand that so let me close this.

Ahh I think elm-hot-loader can be under devDepencies so if you wanna update the PR with only that change I am happy to merge, thank you 👍

elm-hot-loader has originally been under devDependencies. So I have nothing to do for that. 😅

https://github.com/rails/webpacker/pull/1208/files#diff-70f863ebe5733123329d857ce42200ebL25

Thank both of you!