included LRU cache with redis invalidation

test/acceptance/cache_validator.js

@@ -0,0 +1,24 @@
+
+
+var   assert      = require('assert'),
+      tests       = module.exports = {},
+      th          = require(__dirname + '/../test_helper'),
+      CacheValidator = require(__dirname + '/../../lib/cartodb/cache_validator')
+
+var cache = CacheValidator(global.environment.redis);
+
+tests["should get the timestamp it sets"] = function() {
+    var d = new Date().getTime();
+    cache.setTimestamp('mydatabase', 'mytable', d, function() {
+        cache.getTimestamp('mydatabase', 'mytable', function(err, t) {
+            assert.eql(t, d);
+        })
+    });
+}
+
+tests["should get null when timestamp is not set"] = function() {
+    var d = new Date().getTime();
+    cache.getTimestamp('mydatabase', 'mytable2', function(err, t) {
+        assert.ok(t === null);
+    })
+}