[fix] Don't pass empty strings to Faker.fake

Author: Marak

lib/fake.js

@@ -86,7 +86,12 @@ function Fake (faker) {
       params = parameters;
     }
 
-    var result = fn.call(this, params);
+    var result;
+    if (typeof params === "string" && params.length === 0) {
+      result = fn.call(this);
+    } else {
+      result = fn.call(this, params);
+    }
 
     // replace the found tag with the returned fake value
     res = str.replace('{{' + token + '}}', result);