Cleans sessions in leader.py

Closes all open sessions in leader module.
Adds task to bugs file

log/bugs

@@ -1,3 +1,9 @@
+TODO:
+
+Set all folders/parameters in prroperties files and do not have to modify code.
+
+
+
 How is it possible to know which thread raised the error ? Output only says thread.py
 
 enhancement : Session is redefined again and again over the code.

twiderboard/leader.py

@@ -97,6 +97,8 @@ class LeaderBoard():
             top_members = self.get_hashtag_leaders(session, h, self.size)
             leaders.append([h, top_members])
 
+        session.close()
+
         return leaders
 
     def get_hashtag_leaders(self, session, hashtag, size=10):