Reduces headers needed for external includes

hei_main.hpp included hei_isolator.hpp, which requires nearly all
headers in this project to be exported when building a library.

Change-Id: I6013ab53a7ee2b4993526bc4c62b30e8bf5f6702
Signed-off-by: Zane Shelley <zshelle@us.ibm.com>
diff --git a/src/hei_isolation_data.hpp b/src/hei_isolation_data.hpp
index b9a3b75..df07e05 100644
--- a/src/hei_isolation_data.hpp
+++ b/src/hei_isolation_data.hpp
@@ -1,7 +1,8 @@
 #pragma once
 
-#include <hei_includes.hpp>
-#include <isolator/hei_signature.hpp>
+#include <hei_signature.hpp>
+
+#include <vector>
 
 namespace libhei
 {