Log failures to DetachDevice instead of erroring
Log failures to DetachDevice instead of erroring

These commands previously have been ignored, and silently failing when
trying to detach "/var/log." To preserve the previous behavior, we've
changed it to log the error instead.

[#181644134] Update bosh-agent linter to use golangci-lint instead

Signed-off-by: Aram Price <ebc3d4dc278319bab47ffb2bc55fc82b40fcbaf7@vmware.com>

cloudfoundry/bosh-agent,cloudfoundry/bosh-agent