added comments and tests.

opp/core/src/main/java/OPStaffService.java

opp/core/src/main/java/OPStaffServiceImpl.java

opp/core/src/main/java/Operation.java

opp/core/src/main/java/OperationServiceImpl.java

opp/core/src/main/java/OperationTeamImpl.java

opp/core/src/main/java/OperationTeamService.java

opp/core/src/main/java/Repository.java

opp/jdbc-repo-impl/src/main/java/JDBCRepository.java

opp/jdbc-repo-impl/src/test/java/Tests.java