Added null log handler

For those who REALLY like to be in the dark, now you can be completely
unaware.

dmrlink.py

@@ -226,6 +226,9 @@ dictConfig({
         }
     },
     'handlers': {
+        'null': {
+            'class': 'logging.NullHandler'
+        },
         'console': {
             'class': 'logging.StreamHandler',
             'formatter': 'simple'

dmrlink_SAMPLE.cfg

@@ -44,8 +44,10 @@ PRINT_PEERS_INC_FLAGS: 0
 # SYSTEM LOGGER CONFIGURAITON
 #   This allows the logger to be configured without chaning the individual
 #   python logger stuff in dmrlink.py. LOG_FILE should be a complete
-#   path/filename for *your* system. LOG_HANDERLS may be any of the
-#   following, please, no spaces in the list if you use several:
+#   path/filename for *your* system -- use /dev/null for non-file handlers.
+#   LOG_HANDERLS may be any of the following, please, no spaces in the
+#   list if you use several:
+#       null
 #       console
 #       console-timed
 #       file