Consistently use start/end instead of left/right layout properties.

Fixes various RTL language bugs.

Change-Id: I3be9c9c54e4fd14a561f6b38ce1601bc66c8351b

Conflicts:
	res/layout/button_backlight.xml
	res/layout/custom_screencolor.xml
	res/layout/display_color_calibration.xml
	res/layout/display_gamma_calibration_item.xml
	res/layout/screen_color_item.xml
	res/layout/screencolor_settings.xml
	res/layout/vibrator_intensity.xml