Make safe_append= live on AV::OutputBuffer not AS::SafeBuffer

Conflicts:

	actionpack/lib/action_view/template/handlers/erb.rb

actionpack/lib/action_view/template/handlers/erb.rb

@@ -15,6 +15,7 @@ def <<(value)
       super(value.to_s)
     end
     alias :append= :<<
+    alias :safe_append= :safe_concat
   end
 
   class Template

activesupport/lib/active_support/core_ext/string/output_safety.rb

@@ -73,7 +73,6 @@ def html_safe?
 module ActiveSupport #:nodoc:
   class SafeBuffer < String
     alias safe_concat concat
-    alias safe_append= concat
 
     def concat(value)
       if value.html_safe?