Telegram ↔ XMPP federation

[ForNeVeR]

I want to create federated network between our XMPP and Telegram chats. Guys from javascript@cjr have implemented a working bot: https://github.com/jt3k/chat-linker

Here's the plan:

1. Install Docker to ctor (if we haven't done it yet). Decided to host it on cthulhu-3.
2. Dockerize chat-linker (because I don't want to add a global Node.js installation to ctor).
3. Add docker-compose.yml for it (so it'll be easier to restart/rebuild the container). Decided to use just Dockerfile and some instructions.
4. Commit both the Docker environment and docker-compose.yml to this repo; add chat-linker as a submodule if necessary. Do not commit any sensitive credentials to the repository!
5. Clone this repository to ctor, set up the environment, deploy the shits. No need for that because everything is hosted on cthulhu-3.