Align macro definitions using spaces instead of tabs
Fix a crash when parsing dates

Don't attempt to parse a date timestamp if it is nil.
Add reflection helpers and macros to BoxModel

Model property getters are very repetetive. This patchset adds a new macro
and category on NSJSONSerialization to enable dynamic dictionary lookups and
enforcement of type expectations to DRY up the model classes.
Migrate BoxItem, BoxFolder, and BoxFile to the new reflection macro
Remove macros and inline calls to NSJSONSerialization directly in the model getters
Merge pull request #26 from box/refactoring/more-dry-model-properties

Refactoring: more dry model properties