v0.5.0

• Update Backbone to v1.1.2
• Update Underscore to v1.7.0
• Set parent before rendering in CompositeView#renderChild() so child view
  has access to parent for easier event bindings.
• Deprecate Observer#bindTo() and Observer#unbindFromAll() in favor of
  Backbone's Events#listenTo() and Events#stopListening().