ENYO-399: Prevent event propagation for sub-pickers at create time.

Enyo-DCO-1.1-Signed-off-by: Aaron Tam <aaron.tam@lge.com>
Merge pull request #1736 from enyojs/ENYO-399-aarontam

ENYO-399: Prevent event propagation for sub-pickers at create time.

Reviewed-By: Blake Stephens (blake.stephens@lge.com)
Integrated-by: Ryan Duffy (ryan.duffy@lge.com)
ENYO-409: Handle case where date picker has not had a value set yet.

Enyo-DCO-1.1-Signed-off-by: Aaron Tam <aaron.tam@lge.com>