Add support for specifying the primary key of a model.
Add some documentation for primaryKey.
Merge pull request #74 from eventualbuddha/primary-key

Add support for specifying the primary key of a model.
Initial implementation of attribute types
Wrap ajax call inside promise
Merge pull request #75 from alexspeller/wrap-ajax-call-inside-promise

Wrap ajax call inside promise
Merge pull request #73 from alexspeller/add-attribute-types

Add attribute types
Merge upstream