Add Firefox Server Sync SPK

As requested in #567.
This SPK is tested and works on 88f6281 and Bromolow devices, and should work on all others.
Compilation notes:
- Uses built-in web server (paster), as Syno's Apache doesn't support WSGI. This server is not intended for heavy use. I limited the amount of worker threads to 5 in the .ini file, it's set to 69 by default iirc.
- Uses built-in SQLite. Compiling with support for MySQL should be possible, but I need to look into that further (needs SQLAlchemy with MySQL-Python).
- Installation of most modules is done via pip bundle within the virtualenv...it takes about 10 minutes to install on my 212+ :/. After that, it's fine. Might be better to add most modules directly as Python modules to speed things up.

Installation notes:
- As port 80 is not available with Apache enabled, the URL entered during installation should be http://IP:port or http://example.com:port. That same entry must be used for Firefox as well. You'll get 'incorrect username or password' errors while setting up the synchronization otherwise.