Categories for blog post.

There are 6 predefined categories that have to be used for each
post. Links in sidebar redirect to a list filtered by given
category. Several tags can be specified for one blog post.
Visual improvements for blog page.

Removed unnecessary elements on the list of post. Reduced paddings
and margins, so it looks better.
Merge pull request #60 from zaiste/categories

Categories & Visual improvements for blog
Homogeneize Categories view with main blog view
Repaired tags for blog.

Added tags to several articles. Extracted sidebar. Add `All` category
to go back to a list of all articles.
Merge branch 'fix-nulog' of https://github.com/zaiste/nukomeet.com into zaiste-fix-nulog

Conflicts:
	layouts/tag.haml
Merge pull request #61 from zaiste/fix-nulog

Repaired tags for blog
Merge branch 'master' of https://github.com/nukomeet/nukomeet.com
Fix Projects Filters
Fat cleaning!
Set Async Analytics script

Close https://app.asana.com/0/5007701421565/4916371926256
Merge pull request #62 from AdrienGiboire/master

Homogeneize Categories view with main blog view
HAML to SLIM
Merge pull request #63 from AdrienGiboire/haml_to_slim

HAML to SLIM