Added methods on the ApplicationUserManager to remove a user from a role. Custom implementation required because of a bug in the default implementation.
Made use of the RemoveFromRoleByIdAsync to remove a role from the user.
Removed method GetAll from the ApplicationUserManager.
Replaced a call to GetAll with a call to the property Users.
Merge branch 'feature/user-manager' into develop, containing a fix for removing a user from a role and change in UserController::Get implementation.