Update styling to match new Chrome/devtools flat design.

What would you like to be added:

Currently config uses one file per environment (eg. dev, staging, prod, etc) we should move to a multi-file config where we have one folder per environment and config values can be split across multiple files within this folder.

Why is this needed:

For setups where there are

Post description and comments should support markdown.

I believe markdown would be particularly useful to format hyperlinks, lists and quotes.

However, some markdown tags should not be parsed as usual (or not be parsed at all): for example a user should not be able to post a comment formatted with header ("#" character in markdown), because then the comment text would too big.

If you PATCHed to /posts/1, but send payload with a different id:

{
  data: {
    id: 789,
    type: 'posts',
    attributes: { ... }
  }
}

We pay attention to the payload and not the URL - instead let's throw an error when there is a mismatch.