added redis contrib module

sites/all/modules/contrib/dev/redis/README.Predis.txt

@@ -0,0 +1,60 @@
+Predis cache backend
+====================
+
+This module will work with the Predis 1.x version. Any earlier versions
+are unsupported.
+
+This client, for now, is only able to use the Predis PHP library.
+
+The Predis library requires PHP 5.3 minimum. If your hosted environment does
+not ships with at least PHP 5.3, please do not use this cache backend.
+
+Please consider using an OPCode cache such as APC. Predis is a good and fully
+featured API, the cost is that the code is a lot more than a single file in
+opposition to some other backends such as the APC one.
+
+Get Predis
+----------
+
+You can download this library at:
+
+  https://github.com/nrk/predis
+
+This file explains how to install the Predis library and the Drupal cache
+backend. If you are an advanced Drupal integrator, please consider the fact
+that you can easily change all the pathes. Pathes used in this file are
+likely to be default for non advanced users.
+
+Download and install library
+----------------------------
+
+Once done, you either have to clone it into:
+
+  sites/all/libraries/predis
+
+So that you have the following directory tree:
+
+  sites/all/libraries/predis/src/ # Where the PHP code stands
+
+Or, any other place in order to share it:
+For example, from your install profiles libraries folder:
+
+  profiles/example/libraries/predis
+
+If you choose this solution, you have to alter a bit your $conf array into
+the settings.php file as this:
+
+  define('PREDIS_BASE_PATH', DRUPAL_ROOT . '/profiles/example/libraries/predis/');
+
+Connect to a remote host and database
+-------------------------------------
+
+See README.txt file.
+
+Advanced configuration (PHP expert)
+-----------------------------------
+
+Best solution is, whatever is the place where you put the Predis library, that
+you set up a fully working autoloader able to use it. The one being used by the
+Redis module is a default fallback and will naturally being appened to the SPL
+autoloader stack.