Added feature to add content block to headings in sidebar -- rebase

app/helpers/content_blocks_helper.rb

@@ -0,0 +1,9 @@
+module ContentBlocksHelper
+  def valid_blocks
+    options = SiteCustomization::ContentBlock::VALID_BLOCKS.map { |key| [t("admin.site_customization.content_blocks.content_block.names.#{key}"), key] }
+    Budget::Heading.allow_custom_content.each do |heading|
+      options.push([heading.name, "hcb_#{heading.id}"])
+    end
+    options
+  end
+end