DDSim.Random: If no random seed is given we create one randomly

Avoid wasting cycles because the same job is run many times
SystemRandom is not pseudorandom, so this should be unique for time and place and machine and thread

DDSim/Helper/Random.py

 """Helper object for random number generator objects"""
 
+import random
+
 from DDSim.Helper.ConfigHelper import ConfigHelper
 
 class Random (ConfigHelper):
@@ -29,9 +31,14 @@ class Random (ConfigHelper):
       return self._random
     self._random = DDG4.Action(kernel,'Geant4Random/R1')
 
-    if self.seed is not None:
-      self._random.Seed = self.seed
-      self._random.Luxury = self.luxury
+    if self.seed is None:
+      ## System provided random source, truely random according to documentation
+      self.seed = random.SystemRandom().randint(0, 2**31-1)
+      print "Choosing random seed for you:", self.seed
+
+    self._random.Seed = self.seed
+    self._random.Luxury = self.luxury
+
     if self.type is not None:
       self._random.Type = self.type