Read files in binary mode. Fixes #14

RubyGems specs files (Marshal and compressed one) were read with default
mode, causing issues since default mode is 'text' on Windows.

Change code to use convenience method Gem.read_binary for that purpose.
Rakefile didn't work, don't recall the error now.  mirror.rb changes are from a github pull request to fix binary packing/unpacking on windows.
look for missing *spec.rz files in the same fashion we look for missing .gem files
Merge branch 'master' of github.com:lamont/rubygems-mirror

Conflicts:
	lib/rubygems/mirror.rb
Merge pull request #1 from lamont/master

fetch missing *gemspec.rz files