add Overlay sample
add Overlay sample

Also updates other samples using overlays
rename overlay sample and fix up related samples
convert ImageBadgeSample to new overlay design

ENYO-510 will add placeholder support for images so preemptively adding
placeholders in the sample. Also added fixed sizes for the images so
the overlays appear in the right place while loading
use IconButtons in OverlaySample

Issue: ENYO-1641
Enyo-DCO-1.1-Signed-off-by: Ryan Duffy (ryan.duffy@lge.com)

enyojs/enyo-strawman