Listeners incorrectly using "order" instead of "priority"

Some listener descriptors are incorrectly using order="..." instead of priority="...".

They are:

• CoreExtensions.xml (nuxeo-core)
• listeners-contrib.xml (nuxeo-core-test)
• listeners-contrib.xml (nuxeo-quota-core)
• binary-metadata-service.xml (nuxeo-binary-metadata)
• event-listener-contrib.xml (nuxeo-sample-project)