Capture the Chartkick JS and yield it in the layout

So that we can include all the JS at the bottom of
the page without error

app/views/layouts/new_application.html.haml

@@ -37,6 +37,7 @@
     = render partial: "layouts/mailjet_newsletter"
 
     = javascript_include_tag "application", "data-turbolinks-track" => true
+    = yield :charts_js
     - if Rails.env == "test"
       %script{ :type => "text/javascript" }
         (typeof jQuery !== "undefined") && (jQuery.fx.off = true);

config/initializers/chartkick.rb

@@ -0,0 +1 @@
+Chartkick.options[:content_for] = :charts_js