Added a new fonts form social header

This will give a nice change that will bring focus to the social part of
the post
Added new partial

Removed feedburner (only 4 people were registered... wasn't that useful)

I also moved the social aspect to its own partial as it gives more
clarity to the code and it's going to be easier to focus on AB testing
soon enough
Fixed issue with button not spaced and aligned

Was giving too much freedom to these badboys. Should now be spaced and
aligned
Removed white space
Moved most site configuration to yaml

Moving hardcoded string to use choices gem through settings.yml
It also uses the same logic as usual where you have default options in
settings.yml and all those settings can be overriden with
settings.local.yml to set secret only in production and outside
versionning.
Removed unecessary files
Added more default settings
Merging conflict with master

Today's commit on master are useful on this blog as well so porting
those changes here.

Conflicts:
	app/assets/stylesheets/fonts.css.scss
	app/assets/stylesheets/post/post.scss
	app/helpers/application_helper.rb
	app/views/layouts/application.html.erb
	app/views/posts/show.html.erb