Ship the patched pymtp with gPodder (bug 307)

In order to avoid user confusion and because
pymtp disappeared from the upstream website, we
now ship pymtp with gPodder and only depend on
libmtp for MTP support.

README

@@ -49,7 +49,10 @@
 
  Additional dependencies for MTP-based device synchronization support:
 
-   * python-pymtp (libmtp's Python bindings; nick125.com/projects/pymtp)
+   * libmtp (>= 1.0.0)
+     Please note that the previously-required "pymtp" module is now included in
+     the gPodder distribution as "gpodder.gpopymtp", and therefore no longer
+     needed as special dependency. You still need a recent version of libmtp.
 
  Additional dependencies for converting OGGs to MP3s on iPod sync: