fix(association): name as default property
fix(association): name as default property

and do not set association properties if none is defined

https://sweebr.atlassian.net/browse/CM-39

bas080/aurelia-form,RWOverdijk/aurelia-form,bas080/aurelia-form,SpoonX/aurelia-form,SpoonX/aurelia-form,RWOverdijk/aurelia-form