MXS-2243 System tests brings VMs by themselves (#193)

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

maxscale-system-test/envv.h

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdlib.h>
+
+/**
+ * @brief readenv Read enviromental variable, if emtpy - set dafault
+ * @param name Name of the variable
+ * @param format Default value
+ * @return Enviromental variable value
+ */
+char * readenv(const char * name, const char *format, ...);
+
+/**
+ * @brief readenv_int Read integer value of enviromental variable, if empty - set dafault
+ * @param name Name of the variable
+ * @param def Default value
+ * @return Enviromental variable value converted to int
+ */
+int readenv_int(const char * name, int def);
+
+/**
+ * @brief readenv_int Read boolean value of enviromental variable, if empty - set dafault
+ * Values 'yes', 'y', 'true' (case independedant) are interpreted as TRUE, everything else - as FALSE
+ * @param name Name of the variable
+ * @param def Default value
+ * @return Enviromental variable value converted to bool
+ */
+bool readenv_bool(const char * name, bool def);