Build: Kaitai compiler requires at least JDK 8

Author: valery1707

appveyor.yml

@@ -4,8 +4,8 @@ skip_tags: true
 environment:
   MAVEN_VERSION: 3.5.0
   matrix:
-    - JAVA_HOME: C:\Program Files\Java\jdk1.7.0
     - JAVA_HOME: C:\Program Files\Java\jdk1.8.0
+    - JAVA_HOME: C:\Program Files\Java\jdk9
 
 os: Windows Server 2012