determine whether response from docker.buildImage is JSON and if so pipe it through JSONStream.parse

This allows the response stream to be rendered appropriately if a newer version of Docker is used which returns a JSONStream instead of plain text.

In an ideal world, dockerode would be aware and dealing with this, but in its current state it doesn't even have any awareness of different API versions altogether. So we do detection based on the content-type of the response which works here if not everywhere.

The code could be written in a slightly more adventurous form as follows:

```
        if res.headers["content-type"] == "application/json"
          res = res.pipe(JSONStream.parse 'stream')

        res.pipe(process.stdout)
```

which would do avoid some code duplication, but I opted for the clearer form.
ignore the .idea metadata folder that JetBrains editors create. This is purely for the convenience of people who use JetBrains editors like myself. Feel free to merge or ignore.
Fix: add JSONStream to package.json
Merge pull request #19 from resin-io/ignore-dot-idea-folder

ignore the .idea metadata folder that JetBrains editors create. This is ...
add TODOs
Merge pull request #20 from resin-io/handle-json-stream-response

Handle JSON stream responses from buildImage
tiny CoffeeScript tweaks
add comment explaining unnecessary else branch
add missing repository field to package.json
fix erroneous groups example
be more explicit about missing dependencies