Bug 883767 - [Email] Unsupported encoding in some email makes the email client explode. r=asuth

propagate https://github.com/mozilla-b2g/gaia-email-libs-and-more/pull/262
Merge pull request #13864 from asutherland/encoding-explosions

Bug 883767 - [Email] Unsupported encoding in some email makes the email client explode. r=asuth