relvalconsumer: adjust to wikitcms changes
    
    mainly, get event by compose ID not URL. This also removes a
    couple of checks which would prevent creation of nightly events
    after candidate events; we want to start doing this now.
    
    The intent, after this change, is that we will get events for
    candidate composes, and we will also get nightly events created
    after candidate events if the regular conditions are fulfilled
    (it's been >3 days and packages have changed, or it's been >14
    days). There is a possibility here that we'll create nightly
    events for composes that have *older* packages than the most
    recent candidate event, but we'll cross that bridge when we get
    to it. It's a bit tricky to deal with programmatically, but we
    could possibly do something when I have some time.