Set locationType to none in tests

Fixes #2559

- Tests should not affect the url so router location should be `none`
- Testem requires a base URL

Previously we were [setting location to `auto`](https://github.com/teddyzeenny/ember-cli/blob/master/blueprints/app/files/config/environment.js#L32-L33) in test environment so that we get a `<base>` tag during build (which testem needs), and then setting it back to `none` in the `startApp` helper before running the tests. But that last step [was removed](https://github.com/stefanpenner/ember-cli/commit/3568d60d745bd7e3f3672819c85c51918690c6c8), which caused the tests to run with location `auto`, which breaks reloads.

It might be a bit confusing to set `locationType:'auto'` in `environment.js` just to get a `<base>` tag, when actually the tests would run with `locationType: 'none'`.  So I just set location to `none` and added a `<base>` tag anyway.

@rwjblue is it safe to set a `<base>` tag in location `none` or was https://github.com/stefanpenner/ember-cli/commit/de7c6bce2cf6c9d271b2ccc23a2872a4bcff6bc5 fixing a previous issue?