OAK-505: NodeImpl#canAddMixin uses hardcoded list of supported mixin types

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1437944 13f79535-47bb-0310-9956-ffa450edef68
Parametrise types

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1437946 13f79535-47bb-0310-9956-ffa450edef68