[configdb]: Fixed TypeErrorException when get_config with python3 sonic-net#44 (sonic-net#46)

Author: madhupalu

src/swsssdk/configdb.py

@@ -280,6 +280,8 @@ def get_config(self):
         keys = client.keys('*')
         data = {}
         for key in keys:
+            if PY3K:
+                key = key.decode('utf-8')
             try:
                 (table_name, row) = key.split(self.TABLE_NAME_SEPARATOR, 1)
                 entry = self.__raw_to_typed(client.hgetall(key))