Travis: Update node to latest 6 version
Travis: Update node to latest 6 version

ZedTheYeti/Rocket.Chat.Electron,RocketChat/Rocket.Chat.Electron,ZedTheYeti/Rocket.Chat.Electron,RocketChat/Rocket.Chat.Electron,ZedTheYeti/Rocket.Chat.Electron,RocketChat/Rocket.Chat.Electron