Sort cache channels and keys alphabetically

lib/cartodb/cache/model/database_tables_entry.js

@@ -11,13 +11,13 @@ module.exports = DatabaseTables;
 DatabaseTables.prototype.key = function() {
     return this.tables.map(function(table) {
         return this.namespace + ':' + shortHashKey(table.dbname + ':' + table.table_name + '.' + table.schema_name);
-    }.bind(this));
+    }.bind(this)).sort();
 };
 
 DatabaseTables.prototype.getCacheChannel = function() {
     var key = this.tables.map(function(table) {
         return table.dbname + ':' + table.schema_name + "." + table.table_name;
-    }).join(";;");
+    }).sort().join(";;");
     return key;
 };