[fix] Don't assume contacts have an email address
[fix] Don't assume contacts have an email address

Test plan:

Removed the email address from mg's contact and tried to autocomplete it.  No contact appeared, and no errors were generated.
```
_.find(angular.element("input").injector().get("$contacts").list(), function(e){return e.email=="mg@inboxapp.com"}).email = undefined
```

PriviPK/privipk-webapp,Eagles2F/inbox-scaffold-html5,PriviPK/privipk-webapp,Eagles2F/inbox-scaffold-html5,Eagles2F/inbox-scaffold-html5,nylas/inbox-scaffold-html5,PriviPK/privipk-webapp,nylas/inbox-scaffold-html5,nylas/inbox-scaffold-html5,PriviPK/privipk-webapp