The script attempts to install tomcat7, if that's not in apt-cache it will attempt to install tomcat6. If you want to manually specify a tomcat version there's a commented out line you can modify. Have at it.
NOTE: It seems like a lot of people have issues with Tomcat8 for some reason so I removed it from the script. If you're using Tomcat8 and it's working yay, you can keep using it by forcing it via the commented out line.