[Android] Set SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION in the video player

[Martin Storsjö]

On Tue, 16 Apr 2013, XilasZ wrote:

> this might need a check on the API, this flag is API16+.

Fixed.

But I realized that this does require a bit more changes - the controls 
need to be moved up, now they're laid out under the navigation bar. I'm 
not sure how much work it would be to fix that, so I guess it's better to 
revert these two commits for now.

// Martin