Time out when network partition occurs
Time out when network partition occurs

* for download less than 1GB

error result:
```
performing operation get: RequestError: send request failed
caused by: Get https://s3.amazonaws.com/bosh-core-stemcells/vsphere/bosh-stemcell-3363.19-vsphere-esxi-ubuntu-trusty-go_agent.tgz: dial tcp 52.216.0.211:443: getsockopt: connection refused
```

[finishes #143754851](https://www.pivotaltracker.com/story/show/143754851)

Signed-off-by: Brian Cunnie <c96b911daecac34294af5ecfb5cb3aa7cd7901af@pivotal.io>

pivotal-golang/s3cli,pivotal-golang/s3cli,pivotal-golang/s3cli,pivotal-golang/s3cli