Implement ui.makefolder and abort repo.makefolder() in dry-run mode

IMAP, Maildir, and LocalStatus abort if in dry-run mode. IMAP and Maildir
will log that they "would have" created a new folder.

This will probably fail later on as we can not cache messagelists on
folder that don't exist, so --dry-run is not yet safe when new folders
have been created.

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

offlineimap/repository/IMAP.py

@@ -341,11 +341,11 @@ class IMAPRepository(BaseRepository):
             foldername = self.getreference() + self.getsep() + foldername
         if not foldername: # Create top level folder as folder separator
             foldername = self.getsep()
-
+        self.ui.makefolder(self, foldername)
+        if self.account.dryrun:
+            return
         imapobj = self.imapserver.acquireconnection()
         try:
-            self.ui._msg("Creating new IMAP folder '%s' on server %s" %\
-                              (foldername, self))
             result = imapobj.create(foldername)
             if result[0] != 'OK':
                 raise OfflineImapError("Folder '%s'[%s] could not be created. "