fix byte compiling warnings

I got following warning at byte compiling `go-autocomplete.el`.

```
Compiling file /home/syohei/tmp/gomi/go-autocomplete.el at Mon Jun 17 22:15:10 2013
Entering directory `/home/syohei/tmp/gomi/'
go-autocomplete.el:85:1:Warning: (lambda (a b) ...) quoted with ' rather than
    with #'
```

lambda expression does not be needed quote.
Please see this patch.