Remove 'config' as parameter from BaseFolder & derivatives

It is possible to get the config parameter from the Repository() which is
set in BaseFolder, so we set self.config there and remove the various
methods and 'config' parameters that are superfluous.

Signed-off-by: Sebastian Spaeth <Sebastian@SSpaeth.de>
Signed-off-by: Nicolas Sebrecht <nicolas.s-dev@laposte.net>

offlineimap/folder/IMAP.py

@@ -35,7 +35,6 @@ class IMAPFolder(BaseFolder):
     def __init__(self, imapserver, name, visiblename, repository):
         name = imaputil.dequote(name)
         super(IMAPFolder, self).__init__(name, repository)
-        self.config = imapserver.config
         self.expunge = repository.getexpunge()
         self.root = None # imapserver.root
         self.sep = imapserver.delim