Encourage sharing recommended tip recipients

[jameysharp]

If someone I trust suggests some people I might want to tip, I'm much more likely to do it than if I see a random request for money from somebody.

To encourage this kind of social influence, I suggest you:

• Allow Gittip users a place to list people they think are worth supporting. This is different than the list of people they personally are supporting—the two lists might even be disjoint.
• Allow users to watch each other's recommendations.

If I'm watching some other users, that should give me some new insights into where I might want to spend my money:

• Show me an activity stream of my follows' newest recommendations.
• Show me the people who are recommended the most frequently by the people I'm following, as a measure of their relevance to my community.

There are quite a few more discovery tools that could be built on this foundation, but this would be a nice start.

[Changaco]

Closing in favor of #2584.