Move common storage, plot and statistic code to cephlib
diff --git a/wally/config.py b/wally/config.py
index 95ae511..2ec7ba5 100644
--- a/wally/config.py
+++ b/wally/config.py
@@ -1,6 +1,6 @@
 from typing import Any, Dict, Optional, Set
 
-from .common_types import IStorable
+from cephlib.storage import IStorable
 
 
 ConfigBlock = Dict[str, Any]