Fixed Poor Spelling

Geez, @benjic learn to spell
Create Stringer Mixin

The stringer class allows any class to create string based identifiers
based on a common pattern
Make UserStory Stinger-ed

UserStories now use a string based id. The mapper uses the underlying
_id property to map integer based ids within the database.
Implement Models as IdStringers

All models generate string based id's.
Map Numeric Ids to Columns in Persistance

When models are persisted to the SQLite backend the ids are stored as
numerics.
Merge pull request #28 from benjic/id_stringer

String Id's