Stable iterators for DiffSets.
Add tests around use of CopyOnWriterAfterIterationHashSet
Revert fix to MergeNodeAction now that the underlying cause has been fixed in kernel
Added relevant PaxosInstance logging
Formattting fix for shell docs.
Merge pull request #1693 from boggle/2.0.1-cow-diff-sets

[AFTER GA] 2.0.1 cow diff sets
Remove Webadmin test that fails surprisingly in TeamCity.