Notifications

[keelerm84]

We need to provide some mechanism for people to receive notifications. Ideally, we can choose which type of alerts to receive.

Some examples:

• Whenever a new code challenge is created, we should notify everyone
• If someone comments on your code challenge, we should notify you
• Admins should be notified whenever new RSS feeds are added that aren't automatically approved.
• Admins should be notified if a new user registers on the site