Fix for proxied array barfing

 - Added specs for serializing arrays which are transparently proxied through
 another class.
 - Added check to native ext to convert an T_OBJECT to a T_ARRAY if
   possible, and leave it alone otherwise.
 - Updated Rakefile to work with latest (10.0.4)

Let me know if you think this should be done differently. This solution is working for me. By the way thanks for your work getting AMF into C. My app is SO much faster with it.