Java 9+ Issues with URLClassLoader

Hi

I don't know where to post this issue but it seems the new version of Java doesn't play very well with jasperstarter

```
./jasperstarter process /home/user/hello-wiorld.jasper -f pdf -r ~/Desktop -P hello=1
Exception in thread "main" java.lang.ClassCastException: jdk.internal.loader.ClassLoaders$AppClassLoader (in module: java.base) cannot be cast to java.net.URLClassLoader (in module: java.base)
at de.cenote.tools.classpath.ApplicationClasspath.add(ApplicationClasspath.java:72)
at de.cenote.tools.classpath.ApplicationClasspath.add(ApplicationClasspath.java:62)
at de.cenote.tools.classpath.ApplicationClasspath.addJars(ApplicationClasspath.java:127)
at de.cenote.tools.classpath.ApplicationClasspath.addJarsRelative(ApplicationClasspath.java:142)
at de.cenote.jasperstarter.App.processReport(App.java:169)
at de.cenote.jasperstarter.App.main(App.java:102)

```