fix(validation): binary data is ok for strings

lib/instance-validator.js

@@ -365,7 +365,7 @@ InstanceValidator.prototype._validateSchema = function(rawAttribute, field, valu
   }
 
   if (rawAttribute.type === DataTypes.STRING || rawAttribute.type instanceof DataTypes.STRING || rawAttribute.type === DataTypes.TEXT) {
-    if (Array.isArray(value) || (_.isObject(value) && !value._isSequelizeMethod)) {
+    if (Array.isArray(value) || (_.isObject(value) && !value._isSequelizeMethod) && !Buffer.isBuffer(value)) {
       error = new sequelizeError.ValidationErrorItem(field + ' cannot be an array or an object', 'string violation', field, value);
       this.errors.push(error);
     }