v0.2.0

Added

• Email through your SMTP server, set by environment variables or in the
  admin with an encrypted password and a test button.
• Admin alerts: photos waiting for approval, an event's summary, failed
  sign-ins, disk almost full.
• End of the event: guests who left their address get a gallery link; you
  get a summary. On schedule or with End the event now.
• Gallery links protected by a password, with an expiry and a downloads
  switch.

Upgrading

• Events that had already closed are marked as ended, so no end-of-event email
  goes out for past parties.
• New optional variables: SMTP_*, ADMIN_EMAIL, SCHEDULER_INTERVAL_SECONDS.

Full Changelog: v0.1.1...v0.2.0