class Bundler::Installer

def install(options)

installation is SO MUCH FASTER. so we let people opt in.
that said, it's a rare situation (other than rake), and parallel
dependencies might affect the installation of a gem.
the order that the resolver provides is significant, since 
def install(options)
  force = options["force"]
  jobs = installation_parallelization(options)
  install_in_parallel jobs, options[:standalone], force
end