Merge branch 'develop' into matthew/preview_url_ip_whitelist

MANIFEST.in

docs/log_contexts.rst

res/templates/mail-Vector.css

res/templates/mail.css

res/templates/notif.html

res/templates/notif.txt

res/templates/notif_mail.html

res/templates/notif_mail.txt

res/templates/room.html

res/templates/room.txt

synapse/api/auth.py

synapse/api/filtering.py

synapse/app/pusher.py

synapse/config/emailconfig.py

synapse/config/homeserver.py

synapse/config/key.py

synapse/config/registration.py

synapse/config/server.py

synapse/federation/federation_server.py

synapse/federation/transaction_queue.py