Exactly where did you add the allowunsignedmodules entry? I added the entry to my ignition.conf as shown below, and it worked as expected:
wrapper.java.additional.1=-XX:+UseConcMarkSweepGC
wrapper.java.additional.2=-XX:+CMSClassUnloadingEnabled
wrapper.java.additional.3=-Ddata.dir=data
wrapper.java.additional.4=-Dorg.apache.catalina.loader.WebappClassLoader.ENABLE_CLEAR_REFERENCES=false
wrapper.java.additional.5=-Xdebug
wrapper.java.additional.6=-Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8001
wrapper.java.additional.7=-Dignition.allowunsignedmodules=true