Selecting an index for paper-tabs without an event being fired

[Adrian Aioanei]

There should be a way to select an index in a paper-tabs component without firing the iron-select event.

For example, when a paper-tabs is initialised, we set this.$.menu.selected = 0; but we don't want the event to be fired because the outside environment is already adjusted for the first item being selected.

I think the event should fire only when the user manually selects an item in the menu.