add 'paper-menu-content' example for 'dense' (#920)
add 'paper-menu-content' example for 'dense' (#920)


PartCycleTech/ember-paper,cogniteev/ember-paper,miguelcobain/ember-paper,cogniteev/ember-paper,bjornharrtell/ember-paper,miguelcobain/ember-paper,miguelcobain/ember-paper,xomaczar/ember-paper,xomaczar/ember-paper,PartCycleTech/ember-paper,pauln/ember-paper,bjornharrtell/ember-paper,cogniteev/ember-paper,pauln/ember-paper,pauln/ember-paper,xomaczar/ember-paper,bjornharrtell/ember-paper,PartCycleTech/ember-paper