Merge branch 'devel' of https://github.com/tinode/chat into devel

missing comma in docker config template

mark sys and fnd topic as loaded immediately

normalize email to lowercase before using (Unicode case collisions)

fix for breakage in online status due to background subscriptions

explain reason for changing value

Merge branch 'devel'

Merge pull request tinode#315 from tinode/aps-service-ext

Set MutableContent and Alert field on the FCM Aps.

Merge pull request tinode#314 from tinode/deadlock

Fix for a deadlock in hub.join

better error text

(cherry picked from commit a57701b)