Basic command-line tools to export KEK and KDKs

Change-Id: I0975871b6639653e60a2f7ccefaf435147828f33
diff --git a/src/access-manager.hpp b/src/access-manager.hpp
index 6f77d4c..d2a6f74 100644
--- a/src/access-manager.hpp
+++ b/src/access-manager.hpp
@@ -75,8 +75,9 @@
   /**
    * @brief Authorize a member identified by its certificate @p memberCert to decrypt data
    *        under the policy
+   * @return published KDK
    */
-  void
+  Data
   addMember(const Certificate& memberCert);
 
   // void