Authors added.

Blog post can be authored. A short description is automatically
included if post meta section contains `authors` entry, e.g.

    authors:
    - zaiste

Additionally, posts can be filtered by author, e.g. `/nulog/zaiste`
will show only Zaiste's blog posts.
Merge branch 'authors' of git://github.com/zaiste/nukomeet.com into zaiste-authors