Change how server logs are dumped

[kegsay]

Currently it dumps server logs to stdout and only on failure. This can always be spat out if COMPLEMENT_ALWAYS_PRINT_SERVER_LOGS=1. However, this isn't the most discoverable, as both Erik and vdh asked me how to get server logs from Complement in the same day.

It would be better if:

• we always printed server logs,
• to disk,
• based on the hs name,
• and then removed COMPLEMENT_ALWAYS_PRINT_SERVER_LOGS.

For extra discoverability, indicating that server logs are going to file X would be useful.

This would be a breaking change to the Complement API.