DRYed out subscriptions into an adapter. removed support for binding-level subscription logic. added reactive#.get(prop) and reactive#set(prop, val) to support other model implementations and make two-way binding easier
updated binding interpolation to use adapters, added adapter tests, backbone example
updated package.json
update docs
Merge pull request #73 from MatthewMueller/master

Added reactive.get(fn) & reactive.set(fn) adapters and updated internals