Replace ujson with simplejson

synapse/api/filtering.py

synapse/handlers/e2e_keys.py

synapse/handlers/message.py

synapse/http/server.py

synapse/replication/tcp/commands.py

synapse/rest/client/v1/room.py

synapse/rest/client/v2_alpha/sync.py

synapse/rest/media/v1/preview_url_resource.py

synapse/storage/account_data.py

synapse/storage/background_updates.py

synapse/storage/deviceinbox.py

synapse/storage/devices.py

synapse/storage/end_to_end_keys.py

synapse/storage/event_push_actions.py

synapse/storage/events.py

synapse/storage/receipts.py

synapse/storage/room.py

synapse/storage/roommember.py

synapse/storage/schema/delta/25/fts.py

synapse/storage/schema/delta/27/ts.py