Add a "Follow" feature to the UI

[NfNitLoop]

Right now, following a user, and knowing whether you already follow a user, is a bit error-prone. You've got to copy/paste the userID into your Edit Profile page.

The UI should:

• Show you that you're following a user when you view their user profile.
• Offer a Follow button
• The Edit Profile page should accept a user ID and prompt the user asking whether they want to add that ID to their list of follows.