Tabs template should set <tabName>Root with page class reference instead of page name string

Now the template is like below.

```typescript
export class TabsPage {

tab1Root = 'Tab1Page' // Look here
tab2Root = 'Tab2Page'
tab3Root = 'Tab3Page'

constructor(public navCtrl: NavController) { }

}
```

This causes url problem on desktop browser. When the first tab is selected, the url will be changed to something like `http://localhost:8101/#/tab1`. I spend hours to find out the solution: change `'Tab1Page'` to `Tab1Page` and import the class.