Uses tini as PID 1 + another bug fix
This release introduces the use of "tini" as a small init-like process that runs as PID 1. Possibly among other things, tini will reap orphaned processes, which we have discovered is a potential issue in the way we use script_exporter.
This PR also pulls in another bug fix in our fork of script_exporter. There was a type assertion with no error handling which could (and did) cause panics when it failed.