default session() to cookieSession() when a store: is not given

[jonathanong]

migrating from senchalabs/connect#516

[jonathanong]

btw we should just always warn something like memory store is currently being used and is not suitable for production usage. either use a db store or use "cookie-session".

side note: this plugin system is pretty silly. we should be able to just do app.use(require('redis-session')()) and have it work.

[dougwilson]

side note: this plugin system is pretty silly.

lol, yes

@jonathanong May I ask why the memory store is bad?

[dougwilson]

@CelestialWalrus restart your app? all sessions are gone. app accidentally crashes? all session are gone. need to scale your app with cluster? no, your users will randomly be logged out all the time.

@dougwilson Ah, thank you.