Appease golint

# Appease golint

Previously there were around a few dozen items it complained about; this eliminates all of those issues. Functionally, everything should be the same.

```bash
$ GOPATH/bin/golint . | wc -l
       0
$ go test
PASS
ok      apns    0.013s
```

### TODOs

- [ ] code review
- [ ] merge
- [ ] :beers: