Bug 974867 - [MMS]Auto suggestion for email address r=Julien

https://bugzilla.mozilla.org/show_bug.cgi?id=974867
no, if you do this, the test will be skipped.

Instead, we really want to test this. So please set `MockSettings.supportEmailRecipient = true` at the start of the test.
To make things easy, you can put all of them in a sub-suite so that you can have one `setup` that sets this.