Improved Docker support

[jabrena]

http://www.oracle.com/technetwork/java/javase/10-relnote-issues-4108729.html#JDK-8146115
https://blog.docker.com/2018/04/improved-docker-container-integration-with-java-10/

• JVM now recognizes constraints set by container control groups (cgroups)
• Java defines a server class machine as having 2 CPUs and 2GB of memory and the default heap size is ¼ of the physical memory

[jabrena]

docker container run -it -m512M --entrypoint bash openjdk:10-jdk
$ docker-java-home/bin/java -XX:+PrintFlagsFinal -version | grep MaxHeapSize
size_t MaxHeapSize                              = 134217728                                {product} {ergonomic}
openjdk version "10" 2018-03-20

docker run -it --cpuset-cpus="1,2,3" openjdk:10-jdk
jshell> Runtime.getRuntime().availableProcessors()
$1 ==> 3