No validation when adding "participant"

Maya will happily let me add "foobar", even though obviously that's not a valid potential participant/email address.

Launchpad Details: [#LP1353703](https://bugs.launchpad.net/bugs/1353703) Avi Romanoff - 2014-08-06 22:04:09 +0000

---
Want to back this issue? **[Post a bounty on it!](https://www.bountysource.com/issues/44229070-no-validation-when-adding-participant?utm_campaign=plugin&utm_content=tracker%2F60388692&utm_medium=issues&utm_source=github)** We accept bounties via [Bountysource](https://www.bountysource.com/?utm_campaign=plugin&utm_content=tracker%2F60388692&utm_medium=issues&utm_source=github).