appveyor.yml: test for checkstyle-tester
appveyor.yml: test for checkstyle-tester

rnveach/contribution,rnveach/contribution,rnveach/contribution,rnveach/contribution,checkstyle/contribution,rnveach/contribution,rnveach/contribution,Vladlis/contribution,MEZk/contribution,checkstyle/contribution,Vladlis/contribution,checkstyle/contribution,MEZk/contribution,Vladlis/contribution,rnveach/contribution,Vladlis/contribution,checkstyle/contribution,MEZk/contribution,Vladlis/contribution,Vladlis/contribution,MEZk/contribution,checkstyle/contribution,checkstyle/contribution,MEZk/contribution,checkstyle/contribution,MEZk/contribution