Notifications for when a post/comment does well in terms of upvotes

[christianselig]

If a user's post or comment does well, we should send a push notification alerting them of this. Users have asked for this and it matches the Reddit app's functionality here well.

Could do at three tiers: 25 upvotes, 500 upvotes, 1500 upvotes, with a different level of excitement in the notification for each tier.

Only look back for 24 hours, or maybe max 48 hours, because we don't need to introduce the complexity of seeing if a 4 month old post exploded randomly, this is for more recent things.