added possibility to set number of accounts in createAndLoadBank
bumbed up number of threads in tastBackup BackupBank


ndb/src/kernel/blocks/backup/restore/main.cpp:
  fixed return code
ndb/test/ndbapi/bank/Bank.hpp:
  added possibility to set number of accounts in createAndLoadBank
ndb/test/ndbapi/bank/BankLoad.cpp:
  added possibility to set number of accounts in createAndLoadBank
ndb/test/ndbapi/testBackup.cpp:
  bumbed up number of threads in tastBackup BackupBank
ndb/test/src/NdbBackup.cpp:
  some small optimizations