Beginning of infinite scroll for recent permanodes.

This doesn't have a progress meter yet.

Change-Id: Iee089c99ff0fef2b2c724ccd5d6087eb4fa3f087
Merge "Beginning of infinite scroll for recent permanodes."
Import lldb panic fix from upstream

Cherry-pick of fix from https://github.com/cznic/exp/commit/bb1bc282aa8c9218dd81be8a61beeb3381722d64

Fixes https://code.google.com/p/camlistore/issues/detail?id=233

Change-Id: I2779fc719e3ed23e334e084a18b8320610ec2ec3