fixed issue #289 where rolling back to the previous revision where we're on the revision immediately after the published one causes a crash
added a test for the revert to previous (where previous is the live version) functionality
Merge pull request #290 from unikent/bug/fix-revert-revision

Bug/fix revert revision
Admin and User get full field read/write permissions in migration
Merge branch 'develop' of github.com:unikent/programmes-plant into develop
Merge pull request #293 from unikent/develop

Develop into master - done to get round the problems we had with the mistaken merge of the workflow branch into master