fix virtual attributes in insert and update statements

VIRTUAL attributes were accidentally being included in INSERT and UPDATE
statements as OUTPUT variables

lib/dialects/mssql/sql-generator.js

@@ -360,13 +360,15 @@ module.exports = {
     var selFields = [];
     var insertKey = false;
     for (var key in modelAttributeMap) {
-      selFields.push('INSERTED.' + quoteIdentifier( (modelAttributeMap[key].field || key)));
-      if(modelAttributeMap[key].autoIncrement
-        && (valueHash[key] === 'DEFAULT'
-          || valueHash[key] === null)){
+      if (Utils._.isFunction(modelAttributeMap[key].type) &&
+          modelAttributeMap[key].type() === undefined) // VIRTUAL field
+        continue;
+
+      selFields.push('INSERTED.' + quoteIdentifier((modelAttributeMap[key].field || key)));
+      if (modelAttributeMap[key].autoIncrement &&
+          (valueHash[key] === 'DEFAULT' || valueHash[key] === null)) {
         delete valueHash[key];
-      }else if(valueHash[key]
-        && modelAttributeMap[key].autoIncrement){
+      } else if(valueHash[key] && modelAttributeMap[key].autoIncrement) {
         insertKey = true;
       }
     }