Set jenkins user home to /var/jenkins_home
#9 - fix for persistent VOLUME
Reduce image size cleaning up apt
Merge pull request #7 from carlossg/size

Reduce image size cleaning up apt and avoid unnecessary updates
Merge pull request #10 from alex-leonhardt/master

#9 - fix for persistent VOLUME
Merge pull request #5 from aleasoluciones/upstream

Set jenkins user home to /var/jenkins_home
Small improvements and tidying up - deferred slave port setting
Update README.md
clean up and add Volume
Show how to customise
tidy up by moving clean