fixes #7666, #7667, #7668 - errata mail notifications

It gives the user a better idea of what isn't available.  Currently, if all errata are in the current environment, then it would look like this in the e-mail

```
Security: 5 (5)
Bugfix: 5 (5)
Enhancement: 5 (5)
```

I think it's more useful to know that I'm current and there's no action to take.