Suppress landscape bug on android native browser (by suppressing scroll direction change)

- detects android natve browser
- forbids scroll change so that scroll direction is always vertical
- This can be extended to all configurations where horizontal scroll
poses problems (by modifying the test in
Implementation.allowChangeScrollDirection).
ALSO : added test css to make portrait tiles resposive. For now :
desactivated with an ubused ".responsiveV " selector.