Remove email_in_address and email_in_category site settings

The functionality is entirely covered by per-category email in addresses, and the category being a number was confusing people.

db/migrate/20140711193923_remove_email_in_address_setting.rb

@@ -0,0 +1,17 @@
+class RemoveEmailInAddressSetting < ActiveRecord::Migration
+  def up
+    cat_id_r = ActiveRecord::Base.exec_sql("SELECT value FROM site_settings WHERE name = 'email_in_category'").first
+    email_r = ActiveRecord::Base.exec_sql("SELECT value FROM site_settings WHERE name = 'email_in_address'").first
+    if cat_id_r && email_r
+      category_id = cat_id_r["value"].to_i
+      email = email_r["value"]
+      ActiveRecord::Base.exec_sql("UPDATE categories SET email_in = ? WHERE id = ?", email, category_id)
+    end
+
+    ActiveRecord::Base.exec_sql("DELETE FROM site_settings WHERE name = 'email_in_category' OR name = 'email_in_address'")
+  end
+
+  def down
+    # this change is backwards-compatible
+  end
+end