Add parser support for YANG actions

Change-Id: I9e96ae15cee3f990dfa5ec3fac433faf71348e11
diff --git a/src/ast_handlers.hpp b/src/ast_handlers.hpp
index 87cacd1..e583207 100644
--- a/src/ast_handlers.hpp
+++ b/src/ast_handlers.hpp
@@ -232,6 +232,8 @@
 
 struct rpcPath_class;
 
+struct actionPath_class;
+
 struct cdPath_class;
 
 struct set_class {
@@ -260,7 +262,9 @@
 
 struct dump_class;
 
-struct rpc_class;
+struct prepare_class;
+
+struct action_class;
 
 struct exec_class;