Fix unicode handling

omnifocus.rb lacks proper support over non-ASCII project names. Fundamentally, this is an issue of AppScript ruby binding, but it's not maintained any longer and I don't want to touch inside of them (first off, AppScript is Carbon backed and Apple doesn't port them to Cocoa based. So, it's a heritage and it's natural to keep away from maintaing it).

With this PR, you can

 * create non-ASCII named projects properly
 * create/delete non-ASCII named tasks properly under ASCII or non-ASCII named projects

Implementation suggestions are welcomed because I don't know much about Ruby manner (maybe there're better ways to apply UTF-8 on all text).