Provide setup script for people who clone this repo

[zachfedor]

At the Boston hackathon, quite a few folks didn't follow the readme and just cloned this repo instead of running stellar scaffold init. Then, when running npm start, they didn't have the Stellar CLI so the command failed (not to mention Docker or the Scaffold plugin).

Proposed Fix

1. Add a prestart script to package.json that runs a Node script
2. The Node script can check for the existence of Stellar CLI, Scaffold Stellar CLI, and Docker and prompt the user to install them
3. It can also ensure the Docker daemon is running

This can even be helpful for people who ran the init command if their environment has changed in any way.

[tupui]

I don't know, I sort of want to not allow people to do that and force them to go read the docs. What about we print a nice message with links 😅

Or we do the init and do some explaining and show the docs link at the end.

Because I think that in the end there is some education purpose to all of that. It's like people who don't want to go through the dev docs on the Stellar website. I think it's a good investment to do and to push for. Like reading our instructions.

[zachfedor]

I totally agree in theory. People should read, they should educate themselves on the tools they're using.

In practice, we can't prevent people from using it how they expect it to be used. @chadoh and I were talking about this today, and I referenced the book Don't Make Me Think. If people are using our tool "wrong," then we can design some fixes to push them in a better direction.

As for printing out a nice message with links, how do we determine whether or not they're running npm start from a project that used init vs a cloned repo? With the check and prompt for installed dependencies, it doesn't matter and can help both parties.

[tupui]

So you would propose to add a step 4 with some small text and link to the docs? Sounds good to me 👍