chore(travis): Use node 4.x
chore(travis): Use node 4.x

Jupitar/angular-material-calendar,abrahampeh/angular-bootstrap-calendar,asurinov/angular-bootstrap-calendar,danibram/angular-bootstrap-calendar-modded,mattlewis92/angular-bootstrap-calendar,Jupitar/angular-material-calendar,asurinov/angular-bootstrap-calendar,danibram/angular-bootstrap-calendar-modded,mattlewis92/angular-bootstrap-calendar,abrahampeh/angular-bootstrap-calendar