Drop the '-M' option from 'triton ssh' added recently for #52.

A better alternative now is 'ssh $(triton ip <inst>)'.

lib/do_instance/do_ssh.js

@@ -92,13 +92,6 @@ do_ssh.options = [
         names: ['help', 'h'],
         type: 'bool',
         help: 'Show this help.'
-    },
-    {
-        names: ['no-disable-mux', 'M'],
-        type: 'bool',
-        help: 'Do *not* disable usage of SSH connection multiplexing. Using '
-            + 'this option might result in hitting a known issue where '
-            + 'command output is lost. See below.'
     }
 ];
 do_ssh.help = [
@@ -114,10 +107,10 @@ do_ssh.help = [
     '',
     'There is a known issue with SSH connection multiplexing (a.k.a. ',
     'ControlMaster, mux) where stdout/stderr is lost. As a workaround, `ssh`',
-    'is spawned with options disabling ControlMaster. You may use the `-M`',
-    'option to not disable ControlMaster but, with node >=0.12, you will lose',
-    'stdout/stderr output. See <https://github.com/joyent/node-triton/issues/52>',
-    'for details.'
+    'is spawned with options disabling ControlMaster. See ',
+    '<https://github.com/joyent/node-triton/issues/52> for details. If you ',
+    'want to use ControlMaster, an alternative is:',
+    '    ssh root@$(triton ip <inst>)'
     /* END JSSTYLED */
 ].join('\n');