Neilj/fix reap users in postgres

update docker base-image to alpine 3.8

Use recaptcha_ajax.js directly from Google

Revert "support admin_email config and pass through into blocking errors, return AuthError in all cases"

This reverts commit 0d43f991.

Blackify the tests

... because logging *before* reloading means the log message gets lost in the old MemoryLogger

The script recaptcha_ajax.js contains minified non-free code which
we probably cannot redistribute. Since it talks to Google servers
anyway, it is better to just download it from Google directly instead
of shipping it.

This fixes #1932.

send SNI for federation requests

Turns out that cancellation of inlineDeferreds didn't really work properly
until Twisted 18.7. This commit refactors Linearizer.queue to avoid
inlineCallbacks.

Flag to disable HS without disabling federation

 Add helper base class for generating new replication endpoints

more metrics for the federation and appservice senders

Support for room versioning