[Tizen][Runtime]Implement screen-orientation feature.

According to Tizen core spec feature XWALK-1491, add a setting attribute "screen-orientation" in Tizen configure file.
This attribute controls whether screen orietation is locked or not. Its value can be one of "portrait", "landscape", "auto-rotation", and the default value should be "portrait".
Here I just follow the logic of "hwkey" setting which is case-sensitive when comparison. But I also agree with you, the caseless comparison looks better. Thanks @halton