message: [Mod] with self and correct variable name
  with self when invoke a class function. And fileName is right.
diff: @@ -1720,9 +1720,9 @@ class Cluster(object):
  def dumpErrorDetails(self):
  for i in range(0, len(self.nodes)):
  fileName="etc/eosio/node_$02d/config.ini" % (i)
  - dumpErrorDetailImpl(filenme)
  + self.dumpErrorDetailImpl(fileName)
  fileName="var/lib/node_%02d/stderr.txt" % (i)
  - dumpErrorDetailImpl(filenme)
  + self.dumpErrorDetailImpl(fileName)
  def killall(self, silent=True):
  cmd="%s -k 15" % (Utils.EosLauncherPath)
  