Add heuristics for determining evdev device class

These heuristics are similar to those of xf86-input-cmt.

BUG=chromium-os:36634
TEST=see it probes device class correctly from debug output

Change-Id: I9e8a2225ff439608621d3760adde7690ded4b61e
Reviewed-on: https://gerrit.chromium.org/gerrit/38695
Commit-Ready: Che-Liang Chiou <clchiou@chromium.org>
Reviewed-by: Che-Liang Chiou <clchiou@chromium.org>
Tested-by: Che-Liang Chiou <clchiou@chromium.org>