Implement log rotation

[norswap]

Fixes #46

• Implement log rotation, with a default policy of retaining 300 rotation of 3MB or 14 days (files deleted whenever the first one happens) — users can configure this via options and also add overrides (in the form of logrotate commands) per-log-file

• Move libroll to own package and split a few things out (more work to do there to get a real clean layout)

  • The result of command-line args parsing has been moved out to a separate top-level state module.

• Fix "failed to promptly kill subprocess" and generally improve the shutdown logic

• Now warn whenever a service shuts down unintendly — in the future we can implement a restart logic.

• Migrate more log files to the config. Right now the system is that log files name that need to be rotated live in the config, while others are hardcoded, but ultimately it would be good to migrate them too.

• Add new file= mode to lib.run and derivatives — this is not only terser (no more need to open the file ourselves) but it writes by reopening the file every time a write is made. This is necessary for handling archiving of log files via move (not necessary in the default config because log files are compressed by default).

• Really fixed the flaky deployment to temporary geth issue this time — see here for a description.