OPENJPA-2172.  Remove the dependency on the slf4j runtime bundle from openjpa-all.jar.  Also, modified the persistence.xml files for the OpenBooks sample to set the Validation-Mode to None (since it's not being used).  This way, we can avoid the dependency altogether.

git-svn-id: https://svn.apache.org/repos/asf/openjpa/branches/2.2.x@1468067 13f79535-47bb-0310-9956-ffa450edef68