Better loading of attached images

Got rid of that big ugly base64 blob which was only a temporary crutch anyway. Added a png file instead. Use File.read rather than File.open for a 66% reduction in verbosity.

app/models/notifier.rb

@@ -173,15 +173,8 @@ class Notifier < ActionMailer::Base
                   I18n.t("notifier.changeset_comment_notification.commented.subject_other", :commenter => @commenter)
                 end
 
-      attachments.inline['osm_logo_30x30.png'] = {
-        mime_type: 'image/png',
-        encoding: 'base64',
-        content: @@osm_logo_png_bytes,
-      }
-
-      File.open(user_avatar_file_path(comment.author), 'rb') do |file|
-        attachments.inline['avatar.png'] = file.read()
-      end
+      attachments.inline['logo.png'] = File.read(Rails.root.join('app', 'assets', 'images', 'osm_logo_30.png'))
+      attachments.inline['avatar.png'] = File.read(user_avatar_file_path(comment.author))
 
       mail :to => recipient.email, :subject => subject
     end
@@ -216,59 +209,4 @@ class Notifier < ActionMailer::Base
     end
   end
 
-  # FIXME - 2016-12-28 - saintamh - someone please show me a better way to
-  # include this blob in here. If I save it under app/assets, how do I get a
-  # path to it in a portable way?
-  @@osm_logo_png_bytes = <<EOS
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-EOS
-
 end

app/views/notifier/changeset_comment_notification.html.erb

@@ -11,7 +11,7 @@
             <tr>
               <td style="width: 30px; padding: 10px">
                 <a href="<%= @root_url %>" target="_blank">
-                  <%= image_tag attachments["osm_logo_30x30.png"].url, alt: "OpenStreetMap logo", title: "OpenStreetMap", height: "30", width: "30", border: "0" %>
+                  <%= image_tag attachments["logo.png"].url, alt: "OpenStreetMap logo", title: "OpenStreetMap", height: "30", width: "30", border: "0" %>
                 </a>
               </td>
               <td style="padding: 10px 0px">