Remove trailing space from IMAP command

This could be the cause of the error reported in issue 3089.

src/com/fsck/k9/mail/store/ImapStore.java

@@ -908,7 +908,7 @@ public class ImapStore extends Store {
             try {
                 ImapSearcher searcher = new ImapSearcher() {
                     public List<ImapResponse> search() throws IOException, MessagingException {
-                        return executeSimpleCommand(String.format("UID SEARCH *:* "));
+                        return executeSimpleCommand("UID SEARCH *:*");
                     }
                 };
                 Message[] messages = search(searcher, null);