[FAB-9702] Orderer defaults to invalid system chan

The orderer default channel name for the orderer system channel was
recently modified to be test_orderer_system_channel.  Underscores are
not legal characters in channel IDs though, so the orderer panics at
startup.  This CR simply changes the underscores to dashes.

Change-Id: I4e826a5abc4c0d42cda7e362fbd7a6054c044d23
Signed-off-by: Jason Yellick <jyellick@us.ibm.com>

Author: Jason Yellick

orderer/common/localconfig/config.go

@@ -161,7 +161,7 @@ var Defaults = TopLevel{
 		ListenPort:     7050,
 		GenesisMethod:  "provisional",
 		GenesisProfile: "SampleSingleMSPSolo",
-		SystemChannel:  "test_system_channel_name",
+		SystemChannel:  "test-system-channel-name",
 		GenesisFile:    "genesisblock",
 		Profile: Profile{
 			Enabled: false,