Use latest version of Tomcat 8.5.x by default for Docker image.
# Use args for Tomcat image label to allow image builder to choose alternatives
# such as `--build-arg TOMCAT_JRE=jre8-alpine`
#
-ARG TOMCAT_VERSION=8.0.20
+ARG TOMCAT_VERSION=8.5
ARG TOMCAT_JRE=jre8
# Use official maven image for the build
