Bug 851963 - [email] iOS mail client attached images may be treated as embedded images that cannot be viewed because there is no referencing text/html part. r=asuth

land https://github.com/mozilla-b2g/gaia-email-libs-and-more/pull/309
Merge pull request #20488 from asutherland/email-ios-images

Bug 851963 - [email] iOS mail client attached images may be treated as embedded images that cannot be viewed because there is no referencing text/html part. r=asuth