Remove PHPUnit dependency & create shell-script with description for it

bin/dev/setup-phpunit.sh

@@ -0,0 +1,13 @@
+#!/bin/bash
+
+PHPUNIT="$(git rev-parse --show-toplevel)/bin/phpunit"
+
+if ! [ -x "$PHPUNIT" ]; then
+	echo "Install PHPUnit 8"
+	cd /tmp/
+	curl -s -O -L https://phar.phpunit.de/phpunit-8.phar
+	chmod +x phpunit-8.phar
+	mv phpunit-8.phar $PHPUNIT
+fi
+
+echo "Using $PHPUNIT $($PHPUNIT --version)"