fix test case
  improve testing


ndb/test/include/HugoOperations.hpp:
  Partial write (only pk)
ndb/test/ndbapi/testNdbApi.cpp:
  improve testcase
    use writePartial to verify that ops get correctly converted
    (also test negative)
ndb/test/src/HugoOperations.cpp:
  write partial + improve prinout in wait_async