fix: Recognize boxed string as schema environment too

Author: prantlf

lib/validator.js

@@ -30,7 +30,7 @@
 
   function compile (schema, environment) {
     var options = {}
-    if (typeof environment === 'object') {
+    if (typeof environment === 'object' && !(environment instanceof String)) {
       options = environment
       environment = options.environment
     }