OAK-672: Avoid JCR APIs calling other JCR APIs
- Introduce SessionContext providing access to session scoped instances
- Introduce SessionContextProvider as temporary solution for mapping SessionDelegate instances to SessionContext instances

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1456022 13f79535-47bb-0310-9956-ffa450edef68
OAK-672: Avoid JCR APIs calling other JCR APIs
- Clean up checkProtected

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1456023 13f79535-47bb-0310-9956-ffa450edef68
OAK-672: Avoid JCR APIs calling other JCR APIs
- Clean up SessionDelegate

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1456024 13f79535-47bb-0310-9956-ffa450edef68