Move conditional into shared banner partial

[decabeza]

Objectives

A little refactor to avoid always writing if has_banners? every time the partial shared/banner is used.

Before you have to write:

<% if has_banners? %>
  <%= render "shared/banner" %>
<% end %>

Now it's enough with:

<%= render "shared/banner" %>

😌

[javierm]

Great 😄. Thanks a lot!

[javierm]

It looks like I forgot to add this pull request to our project board 🤔. I really hope GitHub implements the option to automatically add new pull requests 😌.