rails/rails — pull request #6303 by korny (2012-05-13 12:52:53+00:00)
Title: require "rubygems" is obsolete in Ruby 1.9.3

Requiring RubyGems does nothing on Ruby 1.9.3, since it is already loaded:

```
ruby -e 'p require "rubygems"'
false
```

So, I think we can remove it safely from boot.rb and other files, since Rails 4 will require Ruby 1.9.3+.