Remove useless shouldVerify assignments

lib/crypto.js

@@ -33,7 +33,6 @@ function Credentials (method) {
     this.context.init();
   }
 
-  this.shouldVerify = false;
 }
 
 exports.Credentials = Credentials;
@@ -48,7 +47,6 @@ exports.createCredentials = function (options) {
   if (options.cert) c.context.setCert(options.cert);
 
   if (options.ca) {
-    c.shouldVerify = true;
     if (Array.isArray(options.ca)) {
       for (var i = 0, len = options.ca.length; i < len; i++) {
         c.context.addCACert(options.ca[i]);