ENYO-2681: models without a schema do not have the _relations hash initialized

Enyo-DCO-1.1-Signed-off-by: Cole Davis <cole.davis@lge.com>
Merge pull request #333 from enyojs/ENYO-2681

ENYO-2681: models without a schema do not have the _relations hash initi...

Reviewed-By: Ben Combee (ben.combee@lge.com)