Fix memory adapter to support lowercase desc order

lib/adapters/memory.js

@@ -87,7 +87,7 @@ Memory.prototype.all = function all(model, filter, callback) {
                 var m = key.match(/\s+(A|DE)SC$/i);
                 if (m) {
                     key = key.replace(/\s+(A|DE)SC/i, '');
-                    if (m[1] === 'DE') reverse = -1;
+                    if (m[1].toLowerCase() === 'de') reverse = -1;
                 }
                 orders[i] = {"key": key, "reverse": reverse};
             });