[boost] B2 5.5.0 release

FYI, the latest (5.5.0) release of B2 is now in the develop branch. It will get to the master branch in the next couple of days if nothing blows up. For what's in the release see: < https://github.com/bfgroup/b2/releases/tag/5.5.0> -- -- René Ferdinand Rivera Morell -- Don't Assume Anything -- No Supongas Nada -- Robot Dreams - http://robot-dreams.net