Finish implementing RM endpoint

- This change causes a 405 to be sent if "m.read_marker" is set via /account_data
 - This also fixes-up the RM endpoint so that it actually Works.

synapse/server.py

@@ -48,6 +48,7 @@ from synapse.handlers.typing import TypingHandler
 from synapse.handlers.events import EventHandler, EventStreamHandler
 from synapse.handlers.initial_sync import InitialSyncHandler
 from synapse.handlers.receipts import ReceiptsHandler
+from synapse.handlers.read_marker import ReadMarkerHandler
 from synapse.http.client import SimpleHttpClient, InsecureInterceptableContextFactory
 from synapse.http.matrixfederationclient import MatrixFederationHttpClient
 from synapse.notifier import Notifier
@@ -133,6 +134,7 @@ class HomeServer(object):
         'receipts_handler',
         'macaroon_generator',
         'tcp_replication',
+        'read_marker_handler',
     ]
 
     def __init__(self, hostname, **kwargs):
@@ -291,6 +293,9 @@ class HomeServer(object):
     def build_receipts_handler(self):
         return ReceiptsHandler(self)
 
+    def build_read_marker_handler(self):
+        return ReadMarkerHandler(self)
+
     def build_tcp_replication(self):
         raise NotImplementedError()