Add UnsafeOrderBy()

Author: mythz

src/ServiceStack.OrmLite/Expressions/SqlExpression.cs

@@ -348,7 +348,11 @@ public virtual SqlExpression<T> OrderBy()
 
         public virtual SqlExpression<T> OrderBy(string orderBy)
         {
-            orderBy.SqlVerifyFragment();
+            return UnsafeOrderBy(orderBy.SqlVerifyFragment());
+        }
+
+        public virtual SqlExpression<T> UnsafeOrderBy(string orderBy)
+        {
             orderByProperties.Clear();
             this.orderBy = string.IsNullOrEmpty(orderBy)
                 ? null