Build logs should not include timestamps

[smarterclayton]

$ osc build-logs ruby-sample-build-4
2015-04-08T18:46:23.663573652Z E0408 18:46:23.662384       1 cfg.go:50] /root/.dockercfg: stat /root/.dockercfg: no such file or directory
2015-04-08T18:46:23.673295305Z I0408 18:46:23.673228       1 sti.go:111] Building 172.30.17.189:5000/default/origin-ruby-sample
2015-04-08T18:46:23.939941363Z Cloning into '/tmp/sti290541991/upload/src'...
2015-04-08T18:47:01.485715788Z I0408 18:47:01.485307       1 sti.go:231] Successfully built 172.30.17.189:5000/default/origin-ruby-sample
2015-04-08T18:47:02.690560758Z E0408 18:47:02.690396       1 cfg.go:50] /root/.dockercfg: stat /root/.dockercfg: no such file or directory
2015-04-08T18:47:02.690560758Z I0408 18:47:02.690420       1 dockerutil.go:22] Pushing 172.30.17.189:5000/default/origin-ruby-sample ...
2015-04-08T18:47:23.347668131Z F0408 18:47:23.346955       1 builder.go:62] Build error: API error (500):  v1 ping attempt failed with error: Get http://172.30.17.189:5000/v1/_ping: dial tcp 172.30.17.189:5000: i/o timeout

Getting timestamps from two sources. It's probably due to the glog prefix, which probably means our STI code needs to stop using glog.

[smarterclayton]

I want us to be doing something like this cockroachdb/cockroach#963

The big one is being able to disable the prefix, everything else is nice to have.