OAK-1015: Optimise path parsing

Imprve the heuristics used to avoid full path parsing for "simple" paths
Also unify the getJcrName() checks against hidden and expanded names

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1538131 13f79535-47bb-0310-9956-ffa450edef68