[sailfish-browser] Set allowedOrientations for ApplicationWindow

Default page orientation is the same as allowedOrientations.
Page components might define as well allowedOrientations. Thus,
those pages will not follow default page orientation. Orientation
of a page's allowedOrientations is masked with
ApplicationWindow.allowedOrientations.
Merge pull request #22 from rainemak/allowedOrientations

[sailfish-browser] Set allowedOrientations for ApplicationWindow