OAK-64: privilege mgt (minor improvement, use constant for constraint violation)

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1470455 13f79535-47bb-0310-9956-ffa450edef68
OAK-51 : Access Control Management (mark test that shows OAK-787 as ignored)

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1470469 13f79535-47bb-0310-9956-ffa450edef68
OAK-51 : Access Control Management (mark test that shows OAK-787 as ignored, revert changes made to other tests)

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1470479 13f79535-47bb-0310-9956-ffa450edef68
OAK-781: Clarify / fix effects of MISSING_NODE as base state of NodeBuilder

Start improving documentation on NodeState/Builder especially about the exists() mechanism

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1470487 13f79535-47bb-0310-9956-ffa450edef68
OAK-781: Clarify / fix effects of MISSING_NODE as base state of NodeBuilder

Better documentation about NodeBuilder, especially the new exists() method