GF-12562: Add disabled support for DataRepeater/List/GridList and GridListImageItem.  Add selected computed property.  Add selection unit tests.
Enyo-DCO-1.1-Signed-off-by: Kevin Schaaf <kevin.schaaf@lge.com>
Fix jshint gripe in unit test.
Enyo-DCO-1.1-Signed-off-by: Kevin Schaaf <kevin.schaaf@lge.com>
Merge branch 'core' into merge-gf12562

Conflicts:
	source/ui/data/DataList.js
Merge pull request #379 from enyojs/GF-12562-kevinpschaaf

GF-12562: Add disabled support for DataRepeater/List/GridList and GridLi...

Fixed merge conflict.

Reviewed-By: Cole Davis (cole.davis@lge.com)