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
The test can now be run outside of the test source directory. Since the
`test_dir` global variable contains the absolute path to the test source,
all copying of configurations and execution of scripts can be done with
minimal changes.
