Use loopback address as default for --hosts

Cherry picking 0293633b0f2815ba7be55c63d6ba6ac6a22a1db7
from 2.5 caused numerous formatting related conflicts.
So did the change manually.

maxctrl/lib/core.js

@@ -46,7 +46,7 @@ program
         alias: 'hosts',
         describe: 'List of MaxScale hosts. The hosts must be in ' +
             'HOST:PORT format and each value must be separated by a comma.',
-        default: 'localhost:8989',
+        default: '127.0.0.1:8989',
         type: 'string'
     })
     .option('t', {