Unable to revert to the original version of the provisioning template
Description of problem:
There's no way to revert to the original version of the template. Once user makes a change, there is a new revision created and user can only revert to this version.
It should be possible to revert to the original by undoing the first revision.
Steps to Reproduce:
1. create or clone a provisioning template
2. save it
3. the 'History' will be empty
3. change the template, save
4. in the History tab, there's the revision containing the diff of the original state and the new state
5. from now on, user can only get to the first changed version (by clicking "revert to this version"), but not to the original version
6. one is unable to get to the original, unchanged version