rrd.py: create output directory if it does not exist yet

rrd.py

@@ -15,10 +15,15 @@ class rrd:
     self.imagePath = imagePath
     self.displayTimeGlobal = displayTimeGlobal
     self.displayTimeNode = displayTimeNode
-    
+
     self.currentTimeInt = (int(time.time())/60)*60
     self.currentTime    = str(self.currentTimeInt)
 
+    try:
+      os.stat(self.imagePath)
+    except:
+      os.mkdir(self.imagePath)
+
   def checkAndCreateIfNeededGlobalDatabase(self):
     """ Creates the global database file iff it did not exist.
     """