Add PathObserver to Observable to support observing key paths on objects
Add Array#delete support for observable arrays
Update to opal
Add specs to ObservableArray
Make ObservableArray a module, and include it into RecordArray
Merge model methods into one simpler file/class
Add loaded/new_record writers to be observerable
Use #loaded= and #new_record= setters to be observable compliant
Merge remote-tracking branch 'upstream/master' into fix_model_loading_from_nested_json

Conflicts:
	opal/vienna/model.rb