Share in social networks

* Add the social buttons gem to the Gemfile

* Initializer and translations for the social buttons

* Add the social buttons assets to the sprockets require

* Add the social buttons in the show debate view

* Spec to lock down the amount of social share buttons to three

app/assets/javascripts/application.js

@@ -15,6 +15,7 @@
 //= require foundation
 //= require turbolinks
 //= require ckeditor/init
+//= require social-share-button
 //= require app
 //= require_tree .
 

app/assets/stylesheets/application.scss

@@ -1,6 +1,10 @@
+/*
+ *= require social-share-button
+ */
+
 @import "foundation_and_overrides";
 @import "fonts";
 @import "icons";
 @import "variables";
 @import "participacion";
-@import "debates";
+@import "debates";