Allow to add author information for articles and episodes.

[swilgosz]

Currently all the episodes, are marked as authored by Sebastian Wilgosz. We don't want that.

We already have a data/team folder, where we can add author's information.

Read these information from md file, and include in articles, dynamically.

Example:

https://github.com/swilgosz/hanamimastery/tree/master/data/episodes/33-semantic-versioning.md

uses author: "fiachetti" as the author's definition.

1. Show author's information

Based on this, author information should be visible on the article's page

Add by <a href="/authors/fiachetti">Federico Iachetti</a> annotation, and the same for other authors in the system.

2. Link Author's information

Create a basic author's page, that includes:

1. Basic information about the author, with social media linked.
2. List of articles/episodes published by this author.
3. Add support for avatars, including default avatar in case no avatar is present.

3. Update article's metadata

Make sure that all the metadata (og:author) points to the correct author.