UX issues and other enhancements here

[Mahaveer1013]

1. Past events must be sorted by event_date instead of created_at.
2. Change the email/password sign-in confirmation mail template.
3. Callback redirect handling.
4. A separate page per event will make it easier to share events and handle referral invites.
5. In events and meetups, wherever we show the location, try to make it a link to Maps if possible.