Copy mongo-cxx-driver from 2.3 in tree. Not hooked up yet.
Add missing files to driver
Hook up included mongo c++ driver

This is a partial solution that requires manually building the driver. A
better solution will come soon, but this works for now.

Also fixed up benchmark.cpp to work with newer driver.
Support new pymongo
Tell bottle.py to pick the best WSGI server automatically
Sort by version (aka label) rather than date to match current usage patterns
Clarify help for --label