Improves the author page

* Displays the user avatar if it exists.
* Only load the 10 latest articles
* Paginate the other articles

Issue #231

TODO:

* Include the 10 latest notes (need to define how)
* Only display the complete bio on the first page.
* On the other page, display the first paragraph of the bio, the photo and the articles.
* Mix articles and contents like on the home page (make it optional?)
Fixes conflict