Running container_test in bazel can't be cached

This tool outputs logs with records like this one:
```
time="2018-11-23T22:18:33Z" level=info msg="Extracting image tar to obtain image file system"
```

These records contain timestamps, therefore, logs have different hash on each execution and my remote-caching cas says there's no files for it's digest. Interestingly enough, local caching *does* work, although I don't really understand how.

`container_test` rule does pass `--quiet` to this binary, but that doesn't seem to work (or does something unrelated to logs).

Possibly related: #52.