improve paramiko integration, replace .mesage for exceptions with str(exc)
diff --git a/wally/utils.py b/wally/utils.py
index 71fbe57..e3fda71 100644
--- a/wally/utils.py
+++ b/wally/utils.py
@@ -62,8 +62,8 @@
         yield
     except Exception as exc:
         if isinstance(exc, types) and not isinstance(exc, StopIteration):
-            templ = "Error during {0} stage: {1}"
-            logger.debug(templ.format(action, exc.message))
+            templ = "Error during {0} stage: {1!s}"
+            logger.debug(templ.format(action, exc))
         raise