OS X

Hey guys, been working on this for a few days.

I've currently released this branch as gem version `1.3.0.osx`: https://rubygems.org/gems/bubble-wrap/versions/1.3.0.osx

```
gem install bubble-wrap -v 1.3.0.osx
```

or in your gemfile:

```
gem "bubble-wrap", "~> 1.3.0.osx"
```

Wanted everyone's feedback on the project structure before it was merged into master. Basically everything is broken into `ios` and `osx` folders where necessary.

To run the specs:

`rake spec osx=true`