[Haml] Don't attempt to reference ActionPack directly.

Closes gh-186

doc-src/HAML_CHANGELOG.md

@@ -3,6 +3,10 @@
 * Table of contents
 {:toc}
 
+## 3.0.8 (Unreleased)
+
+* Fix a bug with Rails versions prior to Rails 3.
+
 ## 3.0.7
 
 [Tagged on GitHub](http://github.com/nex3/haml/commit/3.0.7).

doc-src/SASS_CHANGELOG.md

@@ -3,6 +3,10 @@
 * Table of contents
 {:toc}
 
+## 3.0.8 (Unreleased)
+
+* Fix a bug with Rails versions prior to Rails 3.
+
 ## 3.0.7
 
 [Tagged on GitHub](http://github.com/nex3/haml/commit/3.0.7).

lib/haml/template.rb

@@ -46,7 +46,7 @@ unless Haml::Util.rails_env == "development"
   Haml::Template.options[:ugly] ||= true
 end
 
-if ActionPack::VERSION::MAJOR >= 3
+if Haml::Util.ap_geq_3?
   Haml::Template.options[:format] ||= :html5
 end