OS X support!

And it's about damn time. This is for gems that are using MotionRequire

```ruby
Motion::Require.all(...)  # include files regardless of platform
Motion::Require.all(..., platform: :ios)  # only include if the platform is iOS
Motion::Require.all(..., platform: :osx)  # only include if the platform is OS X
Motion::Require.all(..., platform: [:ios, :osx])  # why yes, this IS redundant!  I added it by accident, figured it was good for "completeness"
```

AND there are SPECS for this bad boy!