Fixed integer return type issue for UDF

Author: sutyag

csharp/Adapter/Microsoft.Spark.CSharp/Sql/Functions.cs

@@ -919,7 +919,7 @@ public static Func<Column, Column, Column, Column, Column, Column, Column, Colum
             {typeof(double), "double"},
             {typeof(float), "float"},
             {typeof(byte), "tinyint"},
-            {typeof(int), "int"},
+            {typeof(int), "integer"},
             {typeof(long), "bigint"},
             {typeof(short), "smallint"}
         };