implement localstorage mixin
adapt application to deal with persisted data
handling data latency
add loading view to sub-module
loading view for contacts list
passing parameters to the loading view
add edit view and navigation
data validation and error display when editing a contact
editing a contact from a modal window
using a layout
implement "new contact" modal view, extending from common base view
implement dedicated dialog region
adapt form's submit button text
implement empty view
create FilteredCollection
implement filtering functionality