Fix digest paramater scanning.

Current scan sometimes took down sites.
Worst case scenario is when a user just clicked "ok" without entering a username. This could take down the entire website.
This is related to the ruby (language) bug:
http://rubyforge.org/tracker/index.php?func=detail&aid=21131&group_id=426&atid=1698

lib/rack/auth/digest/params.rb

@@ -17,8 +17,8 @@ def self.dequote(str) # From WEBrick::HTTPUtils
           ret
         end
 
-        def self.split_header_value(str) # From WEBrick::HTTPUtils
-          str.scan(/((?:"(?:\\.|[^"])+?"|[^",]+)+)(?:,\s*|\Z)/n).collect{ |v| v[0] }
+        def self.split_header_value(str)
+          str.scan( /(\w+\=(?:"[^\"]+"|[^,]+))/n ).collect{ |v| v[0] }
         end
 
         def initialize