Add grpc.WithInsecure in sample
Add grpc.WithInsecure in sample

```
2016/02/22 18:03:47 did not connect: grpc: no transport security set
(use grpc.WithInsecure() explicitly or set credentials)
```

I think it's better to avoid this error and point to the authentication
docs.

avx2/avx2.github.io,avx2/avx2.github.io,wildebeestdev/grpc.github.io,avx2/avx2.github.io,wildebeestdev/grpc.github.io,wildebeestdev/grpc.github.io