Log Message:
Update chat/prosody to 0.9.12.

0.9.12
- Dependencies: Fix certificate verification failures when using
  LuaSec 0.6
- mod_s2s: Lower log message to 'warn' level, standard for
  remotely-triggered protocol issues
- certs/Makefile: Remove -c flag from chmod call (a GNU extension)
- Networking: Prevent writes after a handler is closed

0.9.11
- HTTP parser: Improve buffering of incoming HTTP data and add size
  limits
- sessionmanager: Fix for an issue which caused people to be kicked
  from conferences if mod_smacks was enabled
- Dependencies: Workaround for compatibility with LuaSec 0.6
- MUC: Accept missing form as "instant room" request
- C2S: Fix issues with destroying disconnected connections
- mod_privacy: Fix selection of the top resource(s)
- mod_presence: Make sure both users get each others presence after
  adding each other
- mod_http_files: Fix traceback when serving a non-wildcard path
- mod_http_files: Preserve a trailing slash in paths
- util.datamanager: Fix error handling
- net.server_event: Fix internal socket API to allow writing from
  socket.ondrain callback
- net.server_event: Fix timeout
- net.server_event: Fix traceback due to write during TLS handshake
- net.server_event: Fix buffer length check