Nice to have function async-each

``` Livescript
async-each = (func, arr) -->
      items = arr.slice!
      go = ->
          item = items.splice(0, 1).0
          if item?
             func item, go
      go!
```

example

``` Livescript

[1,2,3] |> async-each (number,done)->
    find-user id: number, (err, user)->
        if user? and confirm 'Are you sure?'
            delete-user number, ->
                done!


```
