THRIFT-727 - C++: what() method of generated exceptions will provide more information

Patch: Anna Dymek <aadymek@gmail.com>
Client: C++

This closes #469
diff --git a/tutorial/tutorial.thrift b/tutorial/tutorial.thrift
index c8710d4..571ab8e 100644
--- a/tutorial/tutorial.thrift
+++ b/tutorial/tutorial.thrift
@@ -113,7 +113,7 @@
  * Structs can also be exceptions, if they are nasty.
  */
 exception InvalidOperation {
-  1: i32 what,
+  1: i32 whatOp,
   2: string why
 }