Updated Drawers to use and support the newer moon.Icon capabilities.
Added new private properties for drawer to represent the closed and open state icon names.
Argument/variable name cleanup and minor spacing changes.

Enyo-DCO-1.1-Signed-off-by: Blake Stephens <blake.stephens@lge.com>
Merge pull request #1581 from enyojs/BHV-13959-blakestephens

BHV-13959: Updated Drawers to use and support the newer moon.Icon capabilities.