Bug 1015297 - [Settings] Update to use gaia-header

Please don't do this ! `simcard_dialog.js` is a generic lib that will be used in different cases to popup the dialog. So in our design, it will try to reference `dialogTitle` to `header h1`. So you should fix this selector to `gaia-header h1` and remove the id - `#call-pin2-dialog-title` in `call_pin2_dialog.html`.