tests: Fix test #4

1) Fix test #4 by deleting all local mailfolders remaining from previous
tests, the mailfolder count will be off, otherwise.

2) Make folder deletion work in python3, it weirdly enough needs to be
quoted like this to work in python3 (I found a python bug about this
somewhere).

Signed-off-by: Sebastian Spaeth <Sebastian@SSpaeth.de>

test/OLItest/TestRunner.py

@@ -158,12 +158,12 @@ class OLITestLib():
                     [^"]*$                # followed by no more quotes
                     ''', d, flags=re.VERBOSE)
                 folder = bytearray(m.group(1))
-                folder = folder.replace(br'\"', b'"') # remove quoting
+                #folder = folder.replace(br'\"', b'"') # remove quoting
                 dirs.append(folder)
             # 2) filter out those not starting with INBOX.OLItest and del...
             dirs = [d for d in dirs if d.startswith(b'INBOX.OLItest')]
             for folder in dirs:
-                res_t, data = imapobj.delete(str(folder))
+                res_t, data = imapobj.delete(b'\"'+folder+b'\"')
                 assert res_t == 'OK', "Folder deletion of {} failed with error"\
                     ":\n{} {}".format(folder.decode('utf-8'), res_t, data)
             imapobj.logout()