Use comma separated lists in MaxCtrl options

Using commas instead of spaces prevents a the misinterpretation of
commands as hostnames. If the `--hosts` option was given just before a
command, it would consume the commands as arguments to the `--hosts` list.

Documentation/Reference/MaxCtrl.md

@@ -41,8 +41,8 @@ All command accept the following global options.
   -u, --user      Username to use                    [string] [default: "admin"]
   -p, --password  Password for the user            [string] [default: "mariadb"]
   -h, --hosts     List of MaxScale hosts. The hosts must be in HOST:PORT format
-                  and each value must be separated by spaces.
+                  and each value must be separated by a comma.
-                                             [array] [default: "localhost:8989"]
+                                            [string] [default: "localhost:8989"]
   -s, --secure    Enable HTTPS requests             [boolean] [default: "false"]
   -t, --timeout   Request timeout in milliseconds    [number] [default: "10000"]
   -q, --quiet     Silence all output                [boolean] [default: "false"]

Documentation/Release-Notes/MaxScale-2.2.1-Release-Notes.md

@@ -155,6 +155,12 @@ behavior is advised.
 The top filter now uses the session ID instead of an internal counter for the
 names of the log file names.
 
+### MaxCtrl
+
+The `-h, --hosts` argument was changed to accept a list of hostnames separated
+by commas instead of spaces. This prevents commands from accidentally being
+interpreted as hostnames.
+
 ## Dropped Features
 
 ## New Features

maxctrl/lib/common.js

@@ -26,6 +26,9 @@ module.exports = function() {
     // servers.
     this.maxctrl = function(argv, cb) {
 
+        // Split the hostnames, separated by commas
+        argv.hosts = argv.hosts.split(',')
+
         this.argv = argv
 
         if (!argv.hosts || argv.hosts.length < 1) {

maxctrl/lib/core.js

@@ -38,9 +38,9 @@ program
     .option('h', {
         alias: 'hosts',
         describe: 'List of MaxScale hosts. The hosts must be in ' +
-            'HOST:PORT format and each value must be separated by spaces.',
+            'HOST:PORT format and each value must be separated by a comma.',
         default: 'localhost:8989',
-        type: 'array'
+        type: 'string'
     })
     .option('s', {
         alias: 'secure',