Remove the APPENDUID hack, previously introduced

As Gmail was only announcing the presence of the UIDPLUS extension
after we logged in, and we were then only getting server
capabilities before, a hack was introduced that checked the
existence of an APPENDUID reply, even if the server did not claim
to support it.

However, John Wiegley reports problems, where the APPENDUID would
be None, and we attempt to go this path (it seems that imaplib2
returns [None] if there is no such reply, so our test here for "!="
might fail. Given that this is an undocumented imaplib2 function
anyway, and we do fetch gmail capabilities after authentication,
this hack should no longer be necessary.

We had problems there earlier, where imapobj.response() would
return [None] although we had received a APPENDUID response from
the server, this might need more debugging and testing.

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

Changelog.rst

@@ -9,6 +9,8 @@ WIP (add new stuff for the next release)
 ========================================
 
 * Fix str.format() calls for Python 2.6 (D. Logie)
+* Remove APPENDUID hack, previously introduced to fix Gmail, no longer
+  necessary, it might have been breaking things. (J. Wiegley)
 
 OfflineIMAP v6.5.4 (2012-06-02)
 =================================