Update Notify spec to use host set in config/gitlab.yml

Fixes failing tests introduced in pull request #824

spec/mailers/notify_spec.rb

@@ -5,7 +5,7 @@ describe Notify do
   include EmailSpec::Matchers
 
   before :all do
-    default_url_options[:host] = 'example.com'
+    default_url_options[:host] = EMAIL_OPTS['host']
   end
 
   let(:recipient) { Factory.create(:user, :email => 'recipient@example.com') }