Make posts nicer

_config.yml

_includes/header.html

_includes/post_link.html

_includes/post_meta.html

_includes/tags_module.html

_layouts/course.html

_layouts/default.html

_layouts/post.html

_layouts/project.html

_layouts/system.html

_layouts/tagpage.html

_posts/2014-09-01-Professorship.md

_posts/2014-11-14-PhD-Defense.md

_posts/2015-04-01-New-Phd.md

_posts/2015-05-08OpenDreamKit.md

_posts/2015-05-15-recruiting.md

_posts/2015-07-17-Best-Paper-Award-at-CICM.md

_posts/2015-07-22-New-Demo-OEIS

_posts/2016-07-11-KWARC-goes-FAU.md

_posts/2016-07-26-Florian-substitute-prof.md