scm: add "path_encoding" method in abstract adapter (#2274, #3462, #2664, #5251).

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@5863 e93f8b46-1217-0410-a6f0-8f06a7374b81

lib/redmine/scm/adapters/abstract_adapter.rb

@@ -91,6 +91,10 @@ module Redmine
           @url
         end
 
+        def path_encoding
+          nil
+        end
+
         # get info about the svn repository
         def info
           return nil