Revert pull request #138

This reverts commit 5438bfc43962aedd57b985f0f692899eda6a4b9f, reversing
changes made to 397258e5dfdd2501c663aef73b36525b1de7c518.

This new approach seems to have a race condition where the message we
add is not always avaialable when the changelist view request is made.
The effect being we get a success message instead of an error message.
Merge pull request #143 from alphagov/revert-handle-delete-errors-in-ui

Revert pull request #138