ENYO-3927: Prevent pressed state from appearing from disabled button.

Enyo-DCO-1.1-Signed-off-by: Aaron Tam <aaron.tam@lge.com>
Merge pull request #200 from enyojs/ENYO-3927-aarontam

ENYO-3927: Prevent pressed state from appearing for disabled button.

Reviewed-By: Ben Combee (ben.combee@lge.com)