Change license shortcut for WTFPL

See SPDX licenses for reference: https://spdx.org/licenses/

Also use Regex to match licenses

lib/license.js

@@ -1,8 +1,11 @@
 var MIT_LICENSE = /ermission is hereby granted, free of charge, to any/;
 var BSD_LICENSE = /edistribution and use in source and binary forms, with or withou/;
+var WTFPL_LICENSE = /DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE/;
 var MIT = /MIT\b/;
 var BSD = /BSD\b/;
 var APACHE = /Apache License\b/;
+var WTFPL = /WTFPL\b/;
+
 
 module.exports = function(str) {
     if (str) {
@@ -14,14 +17,16 @@ module.exports = function(str) {
         return 'MIT*';
     } else if (BSD_LICENSE.test(str)) {
         return 'BSD*';
+    } else if (WTFPL_LICENSE.test(str)) {
+        return 'WTFPL*';
     } else if (MIT.test(str)) {
         return 'MIT*';
     } else if (BSD.test(str)) {
         return 'BSD*';
+    } else if (WTFPL.test(str)) {
+        return 'WTFPL*';
     } else if (APACHE.test(str)) {
         return 'Apache*';
-    } else if (str.indexOf('DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE') > -1 || str.indexOf('WTFPL') > -1) {
-        return 'WTF*';
     }
     return null;
 };