Now ui lookup use `data-ui` attribute. and add `$ui` property
Use `grunt-regarde` for development

but `grunt-regarde` is already deprecated….X(
Fix doc comments
Add `Trait.Observable` alias of `Backbone.Events`
Add `onSetElement` interface to Layout and `Trait.LifecycleCallbacks`
Add traits `UiLookupable` && `ElSettable`
Bump version 0.0.2