Used of field version in badge management

The already existing field `version` for badge is now used.
Version is shown on every page where we display badge information.

Version is an automatically managed attribute for badge.
When you create a badge it is in its first version.

Updating badge doesn't create a new version of it. 
The only way to create a new version of a badge is by updating its awarding rules when it has already been awarded. 
When a badge has already been awarded you'll see a warning message on the edit badge page. A popup will also appear when you'll click on the edit button. 
You won't be able to say you haven't been warned.

Here is what happen when a new version is created:
 * Current badge is "`close`", it means it cannot be awarded/edited anymore
 * New badge is create with current badge informations, including the modification you wanted to apply on the current badge, and with a version number increase by one

For example the version 2 of a badge will replace the version1 of the same badge. And so on the admin badge page you won't see the first version but the second version of the badge. 
You won't have access to the first version of the badge anymore.