Fix indentation for index.html

Nested elements should be indented once (two spaces). http://mdo.github.io/code-guide/#html-syntax

Also, I saw [this commit](https://github.com/frabrunelle/ember-cli/commit/d72da9cd9990a07c5dd652bb758b595fea2bb45d) called "quote consistency" but for HTML it's more common to have double quotes. So I would suggest having double quotes for HTML and single quotes for JavaScript.

And shouldn't the content of title be `<%= namespace %>` instead of `App`?