Add config option to disable printing of container logs

[nhudson]

What this PR does / why we need it:

In some instances ct will stall indefinitely if the log output from the containers is too long. This PR introduces a new configuration option that will disable printing of the container logs.

Which issue this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes #471

Special notes for your reviewer:

I am sure this PR isn't ideal, but I am not really sure how to work around my issue. I can say for sure that since using my patched version of ct where log printing is disabled, I have not had ct hang on any job I have ran locally or in a CI job.

[cpanato]

@nhudson please rebase

thanks for this PR

[cpanato]

can you generate the docs using the doc-gen? will be good as well to fetch the latest code from main

go build -o ct-bin ./ct/main.go

$ ./ct-bin doc-gen
Generating docs...
Done.

[nhudson]

@cpanato thanks! Let me know if there is anything else.

[cpanato]

thanks!