Refactored binary_util methods to be wrapped inside BinaryUtil object.

BinaryUtil can be initialized with bootstrap_dir, baseurls, and timeout; missing parameters are loaded from config.
See John's comment on https://rbcommons.com/s/twitter/r/556: "It might be nice to just clean this up wholesale and construct one with urls and a timeout and make this a full self-contained utility class.  There could be a convenience factory classmethod that takes a Config.  This would have some small ripple to current useages so if you agree but wish to defer, TODO and circle back in a new RB."