Fix caching bug with enyo.Scroller

Previous fix to enyo.Scroller resulted in normal scroller
positioning being lost during hide/show. This moves the zeroing
of scrollTop/Left into the caching code when a reset parameter
is passed in.

Enyo-DCO-1.1-Signed-Off-By: Ben Combee (ben.combee@lge.com)
Merge pull request #594 from enyojs/update-scroller-cache

Fix caching bug with enyo.Scroller

Reviewed-By: Ben Combee (ben.combee@lge.com)