Refactored theme's header controller

@tsanko @hippee-lee putting in the toolbox PR again for **TP story 30002** to refactor the header controller in the theme. The build might fail because of the firebase issue, but I've tested it locally and if the changes looks good, it can be pulled in. Please merge the [associated PR on the method theme]](https://github.com/volusion-angular-themes/method/pull/168) as well