Use CollecTor's index.json for download ('''Alpha''' version); adapt current download to use new date format
We're parsing dates from the CollecTor's Apache directory listings to decide whether or not to fetch a remote file. The CollecTor host was recently upgraded from wheezy to jessie, which apparently changed the date format from dd-MMM-yyyy to yyyy-MM-dd. Adapt to this change.
Obviously, parsing dates like this is very fragile. We should soon switch to using CollecTor's index.json file instead, ideally before the next release.