Sanitizing Plist UTF8 strings #2482

I like to resolve this issue asap. I would appreciate your feedback on the solution.
I'm willing to do whatever it takes to fix this. Let me know if this is the way to do it.

Thank you, Ladi
I prefer @alloy version (`RUBY_VERSION >= '1.9'`) because it will be easier to grep when we will drop support for Ruby 1.8.7