Bug 882916 - [Email] Forward/Reply/Reply All functionality breaks on structured clone failure when e-mail sender already exists and has been cached. r=lightsofapollo

Adds a unit test that fails without the fix and passes with it.  Also adds a
bonus unit test that checks that if there's a contact that lacks a name that
we don't die from that.
Merge pull request #221 from asutherland/contact-cache-hit-fix

Bug 882916 - [Email] Forward/Reply/Reply All functionality breaks on structured clone failure when e-mail sender already exists and has been cached. r=lightsofapollo