Add a simple generator for DTMF

lib/make/network.js

@@ -56,6 +56,18 @@ make.network = {
 
     return parts.join(':')
   },
+  iceServer() {
+    return random.pick([
+      'stun:stun.services.mozilla.com'
+    ])
+  },
+  dtmf() {
+    return random.subset([
+      '*', '#',
+      'A', 'B', 'C', 'D',
+      '0', '1', '2', '3', '4', '5', '6', '7', '8', '9'
+    ], make.numbers.range()).join('')
+  },
   goodHostnames: function () {
     return [
       '0.0.0.0',