Checkpoint commit for OPENDJ-1235 : Migrate configuration framework
* Migrate and fix all unit tests in org.opends.server.admin package
** 18 test cases, 409 tests
** Remove server start in setup method of all test cases
** Test case ValidateConfigDefinitionsTest is disabled for now as it needs schema with config object classes
* Update pom.xml
** Change location of generated messages for managed objects to src/main/resources directory
* Update DirectoryServer class : comments and implementation of some stub methods
* Reformat some classes in opends.server.admin package