Detect windows 8 tablet as a mobile device (Bug #1295422)

Currently it is not seen as a mobile device so tries to use drag/drop
for the page editor - which doesn't work

This patch is designed to detect the windows 8 tablet and make it be a
mobile device.

Change-Id: Ief06642d6777f4701e574f13f9b7d2bdcf30db3e
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>