move SiteText.{head,bottom} to SiteCustomization and remove redundant SiteText.top

db/migrate/20150112172259_migrate_site_text_to_site_customization.rb

@@ -0,0 +1,23 @@
+class MigrateSiteTextToSiteCustomization < ActiveRecord::Migration
+
+  def up
+    execute <<-SQL
+      INSERT INTO site_customizations
+        (name, user_id, enabled, key, created_at, updated_at, head_tag, body_tag)
+      VALUES (
+        'Migrated from Site Text',
+        -1,
+        't',
+        '#{SecureRandom.uuid}',
+        now(),
+        now(),
+        (SELECT value FROM site_texts WHERE text_type = 'top' LIMIT 1),
+        (SELECT value FROM site_texts WHERE text_type = 'bottom' LIMIT 1)
+      )
+    SQL
+  end
+
+  def down
+  end
+
+end