Use 2047

Since channel 0 exists on every connection for negotiation and error
communication. 655365 = (1 << 16) - 1, so 2047 = (1 << 11) - 1.

(cherry picked from commit 7a38981)

Author: michaelklishin

Makefile

@@ -25,7 +25,7 @@ define PROJECT_ENV
 	    %% breaks the QPid Java client
 	    {frame_max, 131072},
 	    %% see rabbitmq-server#1593
-	    {channel_max, 2048},
+	    {channel_max, 2047},
 	    {connection_max, infinity},
 	    {heartbeat, 60},
 	    {msg_store_file_size_limit, 16777216},