Implement Transform class and subclasses

[Glavin001]

See http://emberjs.com/api/data/classes/DS.Transform.html

[Glavin001]

• [x] Date
• [x] ObjectId
• [ ] Boolean
• [ ] Number (there are a few because CoreData supports integers of various precisions)

[Glavin001]

How to convert NSDate into Unix timestamp in Objective C/iPhone?: http://stackoverflow.com/a/3023326

[Glavin001]

How to do math on NSNumber: http://stackoverflow.com/a/15437942

[Glavin001]

Create NSDate from Unix timestamp: http://stackoverflow.com/a/5827263

[Glavin001]

Detect AttributeType and use appropriate Transform: http://stackoverflow.com/a/19818990

[Glavin001]

There is a Transformable AttributeType that should be researched further: http://stackoverflow.com/a/1601546