chore(package): update ember-cli-page-object to version 1.14.1

[begedin]

This is a big one, primarily due to changes in the ember-cli-page-object public API

The major things I had to change to avoid deprecations:

• page.render is deprecated, so this.render has to be used. That means I had to get rid of the renderPage function in all of our tests. The loss is that there is some code duplication now, but the gain is that the tests are far more explicit and easier to read through

• collection API has changed

  • items().count is now items.length
  • items(index).foo is now items.objectAt(index).foo

• the collection definition changed from

items: collection({
  scope: '.foo',
  itemScope: '.bar',
  item: itemDefinitionObject
})

to

items: collection('.foo .bar', itemDefinitionObject)