Set param -name automatically (docker run)

``-name`` ist needed for linking containers, i.e. see http://docs.docker.io/en/latest/use/working_with_links_names/#working-with-links-names
added as ``args << ``
Merge pull request #3051 from mattes/patch-1

provisioners/docker: set param -name automatically (docker run)
UPdate CHANGELOG
provisioners/docker: setting to not auto assign name
provisioners/docker: actual auto assign name logic