Combine seperated custom events into one.
Combine seperated custom events into one.

Actually, status of drawer could be distinguished with this.open
property.
So, custom event do not need to be seperated into onExpand and
onCollapse.

Enyo-DCO-1.1-Signed-off-by: David Um <david.um@lge.com>

PKRoma/enyo,bright-sparks/enyo,beni55/enyo,soapdog/enyo,wikieswan/enyo,soapdog/enyo,zefsolutions/enyo,beni55/enyo,enyojs/enyo,wikieswan/enyo,mcanthony/enyo,zefsolutions/enyo,kustomzone/enyo,PKRoma/enyo,kustomzone/enyo,mcanthony/enyo,bright-sparks/enyo,enyojs/enyo