#672 mapi.BinFromHex does not accept python3 'str' argument

[Christian Kristukat]

mapi.BinFromHex fails to convert a hex string id retrieved from the outlook object model.
Sample code:

from future import print_function
from win32com.client import Dispatch, constants
from win32com.mapi import mapi

ol = Dispatch('Outlook.Application')
inbox = ol.Session.GetDefaultFolder(constants.olFolderInbox)
sid = inbox.Parent.StoreID
mapi.BinFromHex(sid)

yields a

ValueError: FBinFromHex failed - input data is invalid

This happens with build 219 and pyhton 3.4.1