Fix Gcal link to .ics format

[iosenberg]

In redirect/calendar.html

[FiskFan1999]

One thing I liked about how it was before is that the link was on the screen instead of only being available after being redirected, so if it was an ical format link you could right-click and copy link, and paste it into an email application (although usually the computer will be smart enough to open it in this way based on Content-Type and file extention). I think having both is the best idea, having /redirect/calendar.html redirect and also linking directly to the ical format link on each page instead of the link to redirect page