purple-facebook-0.9.4-c9b74a765767

• Add content-type header to all requests, fixes http error 400
• Change error message when sync_sequence_id is missing, for clarity
• Bump orca version. Purely speculative, may not help with anything.

Windows users: get the latest build from the usual place: https://github.com/dequis/purple-facebook/wiki/Installing-on-Windows