Passing the value parameter to the providers

The nconf-redis provider needs the value for some reason, if its absent
this call will fail. It should be there anyway.

lib/nconf/provider.js

@@ -462,7 +462,7 @@ Provider.prototype.save = function (value, callback) {
     //
 
     if (store.save) {
-      return store.save(function (err, data) {
+      return store.save(value, function (err, data) {
         if (err) {
           return next(err);
         }