assigned "localhost" as default connectstring
    added a disconnect() first in connect()
    removed double implementation of connect code, use connect() in NdbRestarter
    removed extra "host=" in connectstring


ndb/include/mgmapi/mgmapi.h:
  removed wrong comment
ndb/test/include/NdbRestarter.hpp:
  removed unused variables
ndb/test/src/NdbBackup.cpp:
  removed double implementation of connect code, use connect() in NdbRestarter
  removed extra "host=" in connectstring
ndb/test/src/NdbRestarter.cpp:
  removed unused variables
  assigned "localhost" as default connectstring
  added a disconnect() first in connect()