0.06 Fri Sep 15 14:55:20 BST 2017
 - support multiple attributes per `has`

0.05 Tue Sep 12 04:40:22 BST 2017
 - test, fix working with non-thunk value

0.04 Tue Sep 12 03:12:48 BST 2017
 - use 'rwp' setter
 - add test of validation

0.03 Wed Sep  6 07:39:03 BST 2017
 - switch back to "before" technique so works with roles
 - add test of roles behaviour

0.02 Wed Sep  6 06:36:49 BST 2017
 - switch to BUILDARGS technique

0.01 Wed Sep  6 06:36:49 BST 2017
 - initial release
