Refactoring the role management interface (error handling still missing).
Patching notification for workspace subscription.
Merge pull request #685 from ngodfraind/refactoring-roles-tool

Refactoring the role management interface (error handling still missing)...
Merge pull request #686 from ngodfraind/notifications-bugfix

Patching notification for workspace subscription.
Merge branch 'master' of https://github.com/claroline/CoreBundle into fixing-messagery