The "sys" module is now called "util". It should have a similar interface.
Express app started on port 4000

node.js:201
        throw e; // process.nextTick error, or 'error' event on first tick
              ^
Error: failed to connect to [localhost:27017]
    at [object Object].<anonymous> (/home/neo/Changer/jip.io/node_modules/connect-mongodb/node_modules/mongodb/lib/mongodb/connection/server.js:189:47)
    at [object Object].emit (events.js:70:17)
    at [object Object].<anonymous> (/home/neo/Changer/jip.io/node_modules/connect-mongodb/node_modules/mongodb/lib/mongodb/connection/connection_pool.js:106:14)
    at [object Object].emit (events.js:70:17)
    at Socket.<anonymous> (/home/neo/Changer/jip.io/node_modules/connect-mongodb/node_modules/mongodb/lib/mongodb/connection/connection.js:301:10)
    at Socket.emit (events.js:67:17)
    at Array.0 (net.js:319:25)
    at EventEmitter._tickCallback (node.js:192:41)