OAK-91 : Implement Authentication Support (wip)

- move loginmodules and configurationutil to corresponding spi-packages in order to ease package export definitions.

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1455952 13f79535-47bb-0310-9956-ffa450edef68
minor improvement (replace <code> by {@code}, replace single char string)

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1455998 13f79535-47bb-0310-9956-ffa450edef68