punycode: switch to userland package

- Closes #967, #969, #513

lib/index.js

@@ -11,7 +11,7 @@ var ParserBlock  = require('./parser_block');
 var ParserInline = require('./parser_inline');
 var LinkifyIt    = require('linkify-it');
 var mdurl        = require('mdurl');
-var punycode     = require('punycode');
+var punycode     = require('punycode/');
 
 
 var config = {

package.json

@@ -41,6 +41,7 @@
     "entities": "^4.4.0",
     "linkify-it": "^4.0.1",
     "mdurl": "^1.0.1",
+    "punycode": "^2.3.1",
     "uc.micro": "^1.0.5"
   },
   "devDependencies": {