Add explicit usage to each command

The yargs framework combined with the pkg packaging causes the executable
name to be mangled on installation. For this reason, the usage should be
explicitly added to each command.

maxctrl/lib/set.js

@@ -23,7 +23,8 @@ exports.builder = function(yargs) {
                                 'Any other states will be overridden by the monitor on the next ' +
                                 'monitoring interval. To manually control server states, use the ' +
                                 '`stop monitor <name>` command to stop the monitor before setting ' +
-                                'the server states manually.');
+                                'the server states manually.')
+                .usage('Usage: set server <server> <state>')
         }, function(argv) {
             var target = 'servers/' + argv.server + '/set?state=' + argv.state
             maxctrl(argv, function(host) {