Move session ticket keys to conf

This is temporary, they will soon be replaced by callbacks.
!!! In this intermediate step security is removed !!!
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 750e89d..20d9c74 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -864,6 +864,10 @@
     const char **alpn_list;         /*!< ordered list of protocols          */
 #endif
 
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
+    mbedtls_ssl_ticket_keys *ticket_keys;       /*!<  keys for ticket encryption */
+#endif /* MBEDTLS_SSL_SESSION_TICKETS */
+
     /*
      * Numerical settings (int then char)
      */
@@ -1055,13 +1059,6 @@
     const char *peer_cn;                /*!<  expected peer CN          */
 #endif /* MBEDTLS_X509_CRT_PARSE_C */
 
-    /*
-     * Support for generating and checking session tickets
-     */
-#if defined(MBEDTLS_SSL_SESSION_TICKETS)
-    mbedtls_ssl_ticket_keys *ticket_keys;       /*!<  keys for ticket encryption */
-#endif /* MBEDTLS_SSL_SESSION_TICKETS */
-
     int client_auth;                    /*!<  flag for client auth.   */
     int verify_result;                  /*!<  verification result     */
 
@@ -1928,14 +1925,14 @@
  *                 to allow generating the ticket encryption and
  *                 authentication keys.
  *
- * \param ssl      SSL context
+ * \param conf     SSL configuration
  * \param use_tickets   Enable or disable (MBEDTLS_SSL_SESSION_TICKETS_ENABLED or
  *                                         MBEDTLS_SSL_SESSION_TICKETS_DISABLED)
  *
  * \return         O if successful,
  *                 or a specific error code (server only).
  */
-int mbedtls_ssl_set_session_tickets( mbedtls_ssl_context *ssl, int use_tickets );
+int mbedtls_ssl_set_session_tickets( mbedtls_ssl_config *conf, int use_tickets );
 
 /**
  * \brief          Set session ticket lifetime (server only)