Remove old log files

[code-asher]

Currently you can infinitely accumulate logs (the ones produced by --log-dir).

Well, maybe not infinitely, if you restart your machine I guess it would reset the pid counter and overwrite old files, but still.

Probably easy enough to just delete everything older than n days? Maybe we only do this if there are > n log files.

[code-asher]

It occurred to me that maybe the cleanup logic should be in the cli since it is the one generating the files? Otherwise we need to implement in the JetBrains plugin as well.

[bcpeinhardt]

Closed with #322