index not updated properly

Hi!

I'm in the process of updating what @cibernox did here https://github.com/cibernox/ember-power-select-collection

In its newest version ember-power-select relies on the `index` yielded property of the `#each` helper.

It appears that this is not playing super well with ember-collection and when power-select filters the list the indexes are not updated properly.

ember-collection exposes an `index` but maybe I'm simply misunderstanding its functionality?

I'll try to create a reproduction repository as soon as I can, in the meantime here's a video from this happening in my company's app

https://gsnaps.s3.amazonaws.com/screencast_2016-05-01_18-02-50.mp4

I'm rendering only the indexes in the list instead of the full content and you can see they're not contiguous

thanks!

Start by trying to reproduce the reported filtering case with ember-power-select-collection or ember-power-select using the yielded index from the #each helper. The issue names no files or tests, so first confirm whether ember-collection's exposed index is meant to update after filtering. Done means a reproducible case shows contiguous, updated indexes after filtering.

Rédigé par le modèle d'indexation à partir du texte de l'issue.