Refactor for latest environment

I want to use this in latest rubymotion environment (ver 2.2) with [clearsightstudio/ProMotion](https://github.com/clearsightstudio/ProMotion), but, I saw a trouble.

ProMotion make us use PM::Delegate class instead of AppDelegate class.
So, RubyMotion will raise superclass mismatch when using ProMotion with motion-stump,
because motion-stump builds simple default [app_delegate.rb](https://github.com/siuying/motion-stump/blob/master/lib/stump/app_delegate.rb) which don't inherit other class.

I make some refactor commit for this repository.

2. clean repository
  1. replace Rakefile's line feed code from CR to LF.
  2. update .gitignore for developer