Bug 848266 - [email] Have MailAPI resolve e-mail addresses to contacts

This has r=@asutherland at https://github.com/mozilla-b2g/gaia-email-libs-and-more/pull/186 and r=me at https://github.com/mozilla-b2g/gaia-email-libs-and-more/pull/138

https://bugzilla.mozilla.org/show_bug.cgi?id=848266