bugfix: JVM was not identified on amd64 builds (closes turnkeylinux/tracker#140)

- added JVM identification for amd64 builds
- added error handling to break the build if JVM cannot is not identified
- configure JAVA_HOME in /etc/default/tomcat (thanks @tssgery!)
  https://github.com/turnkeylinux/tracker/issues/140#issuecomment-30928963