chore(bootstrap): Remove support for old bootstrap mechnanisms

Remove support for bootstrap detection using the element id or the element class. E.g.

```
<div id="ng-app">...</div>
<div class="ng-app: module">...</div>
```

Removes reference to bootstrap using IE7

BREAKING CHANGE:

If using any of the mechanisms specified above, then migrate by
specifying the attribute `ng-app` to the root element. E.g.

```
<div ng-app="module"
```
@IgorMinar will update the PR, note that we will still need 2 forEach (even when these will not be nested) as we need to give priority to `element` over what we find using `querySelector`. This is, if `element` has the attribute `data-ng-app` and within the document there is another element with the attribute `ng-app` then we need to bootstrap `element`