Adding chat system project.

It's a basic chat system library with two hackerling circuits (can be easly extended to more than 2).
An example of main is given in the software/projects/chat_system/ directory.
Merge branch 'master' of https://github.com/slash-dev/hackerling-circuit
Merge pull request #1 from slash-dev/add_chat_system_project

Add chat system project