'build' and 'run_test' copies public ssh keys to all created VMs
Legacy code takes keys from different locations, e.g. ~/build-scripts/team_keys which
causes errors due to lack of such files.
Now public keys goes from file defined on or if not defined
from .ssh/id_rsa.pub of current host machine
maxscale-system-test changed in order to control test environment by itself.
Every test checks which machines are running, compare with list of needed machines
and start new VMs is they are missing in the running machines list.
Tests are executiong MDBCI commands, MDBCI executable should be in the PATH
