* Backport r39213 from trunk [ruby-trunk - Bug #7383]

* lib/rubygems.rb:  Return BINARY strings from Gem.gzip and Gem.gunzip.
  Fixes intermittent test failures.  RubyGems issue #450 by Jeremey
  Kemper.
* test/rubygems/test_gem.rb:  Test for the above.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@39229 b2dd03c8-39d4-4d8f-98ff-823fe69b080e