py3: issues with downloadsize incrementing with a string

[zupd]

In the debug log this message appears every time. Seems like there are issues with incrementing the downloadsize (float) with filesize (a string).

[222-th line] unsupported operand type(s) for +=: 'float' and 'str'
Traceback (most recent call last):
  File "ctfd.py", line 219, in __download
    self.__downloadHandler(data)
  File "ctfd.py", line 210, in __downloadHandler
    self.dlSize += filesize
TypeError: unsupported operand type(s) for +=: 'float' and 'str'