Anti-cache with timestamps and H-Store stats

There are two parts of changes:

1) I implemented an anti-cache mechanism with timestamps. Most of the changes are in AntiCacheEvictionManager.cpp and EvictionIterator.cpp. Some changes of tuple header are in tabletuple.h

2) I fixed the some of the stats in H-Store. I added the feature to track index memory in H-Store using a custom allocator.

The default setting of anti-cache in my branch is to use timestamps. This could be changed with a parameter called "self.ANTICACHE_TIMESTAMPS" in "buildtools.py".