Resolve "feature/ETQ Admin, je veux que ssham selle le vault au signal de fin"

Closes #37 (closed)

ssham/__init__.py

@@ -32,7 +32,17 @@ def handler(signal_received, frame):
     lg.debug("Print stack frames:")
     if app.config['SSHAM_LOG_LEVEL']==10:
         traceback.print_stack(frame)
-    exit(0)
+
+    # Shutdown gracefully
+    try:
+        ssham_vault.seal()
+    except Exception as error:
+        lg.critical("Unexpected error :")
+        lg.critical(f"{str(type(error))}")    # the exception instance
+        lg.critical(f"{str(error.args)}")     # arguments stored in .args
+        lg.debug(f"Stack trace:\n{sys.exc_info()[0]}")
+    finally:
+        exit(0)
 
 
 print(" Starting SSHAM Server...")