NEOCluster.tic() gets a new 'slave' parameter that must be True when a client
node is in 'master' mode (i.e. setPoll(True)). In this case, tic() will wait
that all nodes finish their work and the client polls with a non-zero timeout.

Here, tic(slave=1) is used to wait for the storage to process
NotifyUnlockInformation notification from the master.

Traceback (most recent call last):
  File "neo/tests/threaded/test.py", line 80, in testBasicStore
    self.assertEqual(data_info, cluster.storage.getDataLockInfo())
  File "neo/tests/__init__.py", line 170, in assertEqual
    return super(NeoTestBase, self).assertEqual(first, second, msg=msg)
failureException: {('\x0b\xee\xc7\xb5\xea?\x0f\xdb\xc9]\r\xd4\x7f<[\xc2u\xda\x8a3', 0): 0} != {('\x0b\xee\xc7\xb5\xea?\x0f\xdb\xc9]\r\xd4\x7f<[\xc2u\xda\x8a3', 0): 1}