Updated docs to put e-mail in flow, implemented e-mail testing via admin
Merge pull request #239 from theguardian/email-updates

Add "test e-mail" interface.
api: meter and toggle assignment support.
twitter: don't look for users on keg events.
api: Separate new/update flowmeter.
Always check api_key on drink post.

Issue #243.
v0.9.22