Move REST API test scripts into a common directory

Moved and renamed the starting and stopping scripts from the REST API
tests to a common directory. This way the MaxCtrl tests can use the same
scripts to start and stop MaxScale.

Also moved the test configuration file into the `test/` directory and
changed some of the default directory locations.

test/start_maxscale.sh

@@ -0,0 +1,24 @@
+#!/bin/bash
+
+#
+# This script is run before each test block. It starts MaxScale and waits for it
+# to become responsive.
+#
+
+maxscaledir=$MAXSCALE_DIR
+
+test -z "$MAXSCALE_DIR" && exit 1
+
+# Start MaxScale
+$maxscaledir/bin/maxscale -df $maxscaledir/maxscale.cnf >& $maxscaledir/maxscale.output &
+pid=$!
+
+# Wait for MaxScale to start
+for ((i=0;i<60;i++))
+do
+    $maxscaledir/bin/maxadmin help >& /dev/null && break
+    sleep 0.1
+done
+
+# Give MaxScale some time to settle
+sleep 1