Removed breakpointer and Binding.of_caller in favor of relying on ruby-debug by Kent Sibilev since the breakpointer has been broken since Ruby 1.8.4 and will not be coming back [DHH]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@6611 5ecf4fe2-1ee6-0310-87b1-e25e094e27de