break up destroy methods into reusable pieces, and for better V8 optimizing
fix
break out bodies of for in statements into optimizable functions
optimize #augmentProperties

unfortunately we are doing a .call to apply this function to WBModel’s
context, so the optimizable function has to be defined in side
#augmentProperties itself … maybe augmentProperties should probably be
a mixin that can be included anywhere, not just reserved for WBClass
use toArray .. tiny functions == good
Merge pull request #25 from wunderlist/v8-optimizing

V8 optimizing