Promtail - contribution

I like the way was taken by the Loki project which is closely related to what Prometheus looks like but in the logs area. The natural choice regarding Loki is Promtail, which ships the logs. Promtail not only ships logs but also lets you customize what is sent to Loki. One of its options is to drop logs, which shouldn’t be stored in Loki, but it was somehow limited ie. you cannot do complex matches. So I decided to improve it in a similar way to what Prometheus isdoing, effect of my improvements was recently merged… after couple of months ;)