loadAndWaitForAureliaPage with custom bootstrap

I'm guessing this plugin isn't used much anymore, so fixing this isn't the highest priority, but I ran into a problem and I thought I'd at least document it.

The `loadAndWaitForAureliaPage` function [checks for the existence](https://github.com/aurelia/protractor-plugin/blob/1.0.6/index.js#L61) of the `[aurelia-app]` attribute to see whether Aurelia bootstrapping is complete yet. I'm guessing this is based on a standard bootstrap, because when I checked our app the attribute never appears and we bootstrap manually. (Specifically, we do `aurelia.setRoot("src/app", document.body)`.)

The issue identifies index.js in v1.0.6, around line 61, and the loadAndWaitForAureliaPage entry point; start there and reproduce with an app calling aurelia.setRoot("src/app", document.body). The report does not define the desired custom-bootstrap behavior or a test, so those need agreement before implementation; done should be validated against that agreed behavior.

Written by the indexing model from the issue text.