Support project upgrade-rollback

[otsakir]

background stuff

RVD projects are upgraded when a new binary is installed introducing a new project version. This only happens when a project is saved or when the new version introduces backwards incompatible changes. Whatever the reason, a backup file of the upgraded project is kept. Initially, this provided the administrator a means to revert project is case of a binary rollback.

We can utilize this mechanism to allow a user to control this kind of rolling back. When a project fails opening because of wrong version and a compatible project backup exists, an message/option to revert could be given to the user. Also, the actual API to do the revert is needed.

It's important to handle this kind of rolling back in the project editing/details view and not in the project manager project list (since we don't know whether this list will stay in RVD or not).