Bug 825538 - [email/activesync] Need to allocate unique device ID's for multi-device access to ActiveSync. r=squib

land https://github.com/mozilla-b2g/gaia-email-libs-and-more/pull/313
Merge pull request #20525 from asutherland/email-as-dev-id

Bug 825538 - [email/activesync] Need to allocate unique device ID's for multi-device access to ActiveSync. r=squib