Merge pull request #8 from jasongrout/backbone-flat

options on child views and automatically accumulating _keys from superclasses
s/comm_id/model_id (left over from before)
Updated comm id comments in view to model id
Completely remove cell from model and view.
Missing view argument when recursively calling widgetmanager.callbacks(view)
Renamed widget js files
Updated require.js references
Removed ViewWidget
add/remove_class now can accept a list of classes
s/Widget/DOMWidget s/BaseWidget/Widget
s/default_view_name/view_name
s/_handle_widget_constructed/_call_widget_constructed
Removed sync_method parameter from backbone msg spec
Added callbacks method to view
Merge remote-tracking branch 'jdfreder/widget-msg' into backbone-flat
s/widget.js/init.js
renamed:    basic_widgets.js -> init.js
renamed:    init.js -> widget.js
Remove first three lines of repr widgets
Fixed _send so it can open a comm if needed.
It no longer returns anything.
Remove view_name from display