Adding an example project

Issue reference: #69 

- Added an example project
- Linked SugarRecord
- Added `StacksTableViewController` which displays all the Stack types. Right now I've only added CoreData.
- Added `StackTableViewController` as a based TableViewController to be used for each stack. In a subclass, you can just create the stack and define the `entityClass`, and you are good to go. Adding and deleting is supported right now.

Thoughts:

- Can all the Entity Classes share one NSManagedObject subclass, or is that not possible? I have not looked at the other stacks yet, but I do not believe so. Right now I have one created for CoreData, but if we have to make multiple we should make a simple protocol so they all have the same properties.