use prepend, since fb_graph2 doesn't need ruby 1.9.x support

close #102

NOTE: we still have alias_method_chain in rack-oauth2 etc.

lib/patch/rack/oauth2/util.rb

@@ -1,14 +1,17 @@
 # NOTE: Authorization code given via FB JS SDK needs blank string as redirect_uri
+
 module Rack::OAuth2::Util
   class << self
-    def compact_hash_with_blank_redirect_uri(hash)
-      original_redirect_uri = hash[:redirect_uri]
-      result = compact_hash_without_blank_redirect_uri hash
-      if original_redirect_uri
-        result[:redirect_uri] ||= original_redirect_uri
+    module ComcactHashWithBrankRedirect
+      def compact_hash(hash)
+        original_redirect_uri = hash[:redirect_uri]
+        result = super
+        if original_redirect_uri
+          result[:redirect_uri] ||= original_redirect_uri
+        end
+        result
       end
-      result
     end
-    alias_method_chain :compact_hash, :blank_redirect_uri
+    prepend ComcactHashWithBrankRedirect
   end
 end