`gem push --host`
* lib/rubygems/gemcutter_utilities.rb: ditto.
* test/rubygems/test_gem_commands_push_command.rb: Test for the above.
* test/rubygems/test_gem_gemcutter_utilities.rb: ditto.
* lib/rubygems/config_file.rb: Abort if the `gem push` credentials
file has insecure permissions.
* test/rubygems/test_gem_config_file.rb: Test for the above.
* lib/rubygems/ext/builder.rb: Do not look for Gemfile, Isolate, etc.
while building gem extensions.
* lib/rubygems/package.rb: Unset spec and files list if a gem's
signatures cannot be verified.
* test/rubygems/test_gem_package.rb: Test for the above.
* lib/rubygems/specification.rb: Reduce use of eval.
* lib/rubygems/test_case.rb: ditto.
* test/rubygems/test_gem_specification.rb: Test setting
specification_version for legacy gems. Dup Gem.ruby before
untainting in case it's frozen.
* lib/rubygems.rb: Reduce use of eval. Only read files when looking
for Gemfile, Isolate, etc.
* test/rubygems/test_gem.rb: Test for the above.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39055 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
