correctly set flag during destroyAll, allow destroyAll local-only including fetchAndDestroyLocal as well as update documentation

Enyo-DCO-1.1-Signed-Off-By: Cole Davis (cole.davis@lge.com)
ensure that records being destroyed are actually model instances

Enyo-DCO-1.1-Signed-Off-By: Cole Davis (cole.davis@lge.com)
update changelog

Enyo-DCO-1.1-Signed-Off-By: Cole Davis (cole.davis@lge.com)
Merge pull request #586 from enyojs/ENYO-3610-coledavis

Fix for: ENYO-3610

Reviewed-By: Ben Combee (ben.combee@lge.com)