Accessible build logs

Adding option to retrieve logs form a build.
Usage:
        `kube buildLogs --id="buildID"`
@smarterclayton implementing the redirect method is doable, but not using the client if retrieving logs shall be streamed. The problem is that I cannot use the client for streaming, cause I need from the Request struct the io.Reader before I send the request, which is private, thus cannot be retrieved.
So there are two options:

1.  Modify this in the upstream, by adding something like DoStream method, or making finalURL() public, or making Request struct params public.
2.  Use the client as suggested, but the logs could not be stream, just snapshoted.

Thoughts ?