Investigate Matrix 1.0 / Synapse 0.99, 1.0 changes

[ulope]

Problem Definition

As announced during FOSDEM 2019, Matrix has released v1.0 of their spec and also v0.99 of the Synapse homeserver (v1.0 planned for March).

Most notable changes:

• No more self-signed certificates for S-S federation traffic, everything is Letsencrypt now
• Rooms "version 3", room ids will change to a base64 encoded content hash

We need to investigate what impact (if any) those changes will have on our use of Matrix:

• Certificates for local federation used for tests
• Possible changes in room discovery due to room ID change
• ???
• Once the switch has been made the psycopg2 pinning in requirements/requirements-dev.in should be removed.

[konradkonrad]

I have a couple flaky tests in an unrelated PR since after the upgrade to 0.99:

• https://circleci.com/gh/raiden-network/raiden/46534#tests/containers/11
• https://circleci.com/gh/raiden-network/raiden/46535#tests/containers/5