Debug log reason why module can't be imported.

Usually this will be because someone just wants to use the wheel, but
during development this can be caused by other issues, and shouldn't
be silenced.

blender_cloud/wheels/__init__.py

@@ -18,8 +18,9 @@ def load_wheel(module_name, fname_prefix):
 
     try:
         module = __import__(module_name)
-    except ImportError:
-        pass
+    except ImportError as ex:
+        log.debug('Unable to import %s directly, will try wheel: %s',
+                  module_name, ex)
     else:
         log.debug('Was able to load %s from %s, no need to load wheel %s',
                   module_name, module.__file__, fname_prefix)