Create a pipeline for gettor statistics

We have some functionality in place for collecting statistics for GetTor (see https://dip.torproject.org/torproject/anti-censorship/gettor-project/gettor/issues/10), but there is some work to be done in collecting these stats at regular intervals and exporting them to CollecTor (if we decide that's what we want).

This ticket is for regularly collecting and putting GetTor statistics into a format that's useful for us and others.