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
MXS-2236 Add own long test and possibility to run tests under Valgrind
Long test executes INSERT queries, transactions, prepared statements in parallel to create weird load on Maxscale to catch crashes and leaks
Test is not included into ctest scope. Test should be executed manually. For BuildBot (and also for run_test.sh) 'test_set' should be set 'NAME# ./long_test'
Time to run test is defined by 'long_test_time' variable (in seconds)
Possibility to run Maxscale under Valgrind is also added. To run Maxscale under Vaslgrind 'use_valgrind=yes' variable have to be defined
