one contribute.json for the whole thing

@pmclanahan r?

So, we used to have a two `contribute.json`. I guess we thought we'd have one for the project and one for the validator app. That's silly. 

Also, I wanted the `contribute.json` to exist in the root directory but to make it available in the stackato app, it'd have to copy from the parent directory into the stackato `./app` directory.