Integrate raiden-libs to avoid duplicating code and effort

[loredanacirstea]

Problem Definition

https://github.com/raiden-network/raiden-libs was created to aggregate common tools used across raiden-network repositories.
It should be integrated in raiden to avoid duplicating code and effort. E.g. raiden-network/raiden-libs#50

[ulope]

Just FYI: This is already starting in #1373 with the gevent matrix client