Split the IMAP folders

This patch modifies two files. First, we need split using '', not '""'.
Else we don't split anything.

OTOH, we need convert the bytes to string, then we can parse the folder
names.

offlineimap/imapserver.py

@@ -599,7 +599,7 @@ class IMAPServer(object):
                 imapobj.capabilities = tuple(dat[-1].upper().split())
 
             if self.delim == None:
-                listres = imapobj.list(self.reference, '""')[1]
+                listres = imapobj.list(self.reference, '')[1]
                 if listres == [None] or listres == None:
                     # Some buggy IMAP servers do not respond well to LIST "" ""
                     # Work around them.