GF-12660 : Slider Samper drag issue

In Slider Sampler in Onyx, slider value isn't reach until max value. The
reason is Math.floor func is used. So I did change from Math.floor to
Math.ceil.
Enyo-DCO-1.1-Signed-off-by: Changgi Lee <changgi.lee@lge.com>
Merge pull request #177 from sojujazz/GF-12660-sojujazz

GF-12660 : Slider Samper drag issue

Reviewed-By: Ben Combee (ben.combee@lge.com)