Refactor ripple_overlay:
  * Use rvalue move to receive accepted sockets
  * Split asio dependent APIs to their own class and file
  * Update documentation
  * Organize code into different files
  * Make some members private
  * Rename things for clarity
Remove obsolete TODO files
Fix 64-bit Visual Studio build
Add [max_peers] doc to example cfg
Convert all uses of boost::tuple to std::tuple
[WIP]  I've removed boost::unordered_map from all parts
of rippled except Peers.cpp.  I've run out of time to
do this now.
Continue removing use of boost::unordered_map
[WIP] Continuing to work on getting rid of boost::unordered_map
[FOLD] Fix vs2013 compile and move UnorderedMap.h
Make Destroyer safer.
Further work on getting off of boost::unordered_map.
Convert all uses of boost::tuple to std::tuple
Fix warning in fnv1a on 32 bit platforms.
RIPD-203.