Introduce osmo-gsm-tester docker setup This set up allows running a typical osmo-gsm-tester set up with a main unit (ogt-master) attached to one (or more) slaves where resources are located and processes are run. As an example, current config allows running an iperf3 test over an srsLTE stack using the ZeroMQ backend. Change-Id: Iac7c0b613048ce332642d3957c55cc7c53b56d42
