Show invitee username

![screenshot from 2014-12-10 14 36 39](https://cloud.githubusercontent.com/assets/464938/5376715/fcfbe8a2-8079-11e4-8123-47a75219c440.png)
Merge PR in ix first: stellar/ix#424
Closes: #1005
This hack is a red flag that suggests that the inviteStatus should be content in the template. Then you could use a variable binding.

More importantly, the username almost certainly does not belong here. It probably belong next to the email address. I would get some UX feedback on this.